Early life

Li Shimin was born in 598 at Wugong, in modern Xianyang, Shaanxi. His father Li Yuan, the Duke of Tang, was a general of the Sui dynasty, and a nephew, by marriage, to Sui's founding emperor Emperor Wen. Li Shimin's grandmother Duchess Dugu was a sister of Empress Dugu, both of whom were daughters of Dugu Xin, a major Xianbei general during Sui's predecessor dynasty Northern Zhou. Li Shimin's mother, Li Yuan's wife Duchess Dou, was a daughter of Dou Yi, the Duke of Shenwu, and his wife, Northern Zhou's Princess Xiangyang. Li Shimin was also of partial Xianbei descent. Duchess Dou bore Li Yuan four sons—an older brother to Li Shimin, Li Jiancheng, and two younger brothers, Li Yuanba (李元霸), who would die in 614, and Li Yuanji – and at least one daughter (the later Princess Pingyang). Li Yuan named Li Shimin "Shimin" as a shortened form of the phrase "save the earth and pacify the people" (濟世安民 jìshì ānmín). Li Shimin apparently showed talent early in his life, and in 613, the official Gao Shilian, impressed with him, gave him a niece (the later Empress Zhangsun) in marriage as his wife; he was 14 and she was 12. In 615, when Emperor Wen's son and successor Emperor Yang was ambushed by Eastern Turkic (Dongtujue) forces under Shibi Khan at Yanmen Commandery (present-day Daixian in Shanxi), a general call was made for men to join the army to help rescue the emperor. Li Shimin answered that call and served under the general Yun Dingxing, apparently doing so with distinction. In 616, when Li Yuan was put in charge of the important city of Taiyuan, he brought Li Shimin with him to Taiyuan, while leaving at least three other sons – Li Jiancheng, Li Yuanji, and Li Zhiyun (, by Li Yuan's concubine Lady Wan) – at the ancestral home Hedong (, in modern Yuncheng, Shanxi).

Participation in the rebellion against Sui rule

Emperor Yang was soon dissatisfied with Li Yuan and Wang Rengong (王仁恭), the governor of Mayi Commandery (, roughly modern Shuozhou, Shanxi), over their inability to stop Eastern Turkic incursions and the growing strength of agrarian rebels, particularly the Eastern Turkic-supported Liu Wuzhou, who soon rose against Wang, killed him, and captured Emperor Yang's secondary palace near Taiyuan. Li Yuan also became fearful of a prophecy that the next emperor would be named Li—Emperor Yang had previously killed another official, Li Hun, and Li Hun's clan over his fear that Li Hun's nephew, Li Min (李敏), would seize the throne.

Fearful for his life, Li Yuan considered rebellion. However, he did not know that Li Shimin had also been secretly discussing plans for rebellion with Li Yuan's associates Pei Ji and Liu Wenjing. Once Li Shimin's plans matured, he had Pei inform Li Yuan of them—and also had Pei warn Li Yuan that if it were revealed that Li Yuan had had sexual relations with some of Emperor Yang's ladies in waiting at the secondary Jinyang Palace (, which Pei was in charge with and had allowed Li Yuan to do so), all of them would be slaughtered. Li Yuan agreed to rebel, and after secretly summoning Li Jiancheng and Li Yuanji from Hedong and his son-in-law Chai Shao (柴紹) from the capital Chang'an, he declared a rebellion, claiming to want to support Emperor Yang's grandson Yang You the Prince of Dai, nominally in charge at Chang'an with Emperor Yang at Jiangdu (江都, in modern Yangzhou, Jiangsu), as emperor. He made both Li Jiancheng and Li Shimin major generals and advanced southwest, toward Chang'an. He gave Li Shimin the title of Duke of Dunhuang. After defeating local Sui forces loyal to Emperor Yang, he defeated a Sui army of 30,000 men under the command of a veteran general of the wars in Korea outside of modern-day Beijing.

However, when Li Yuan arrived near Hedong, his army was bogged down by the weather. With food running out, there were rumors that the Eastern Turks and Liu Wuzhou would attack Taiyuan. Li Yuan initially ordered retreat, but at the earnest opposition by Li Jiancheng and Li Shimin, continued to advance. After defeating Sui forces at Huoyi (霍邑, also in modern Yuncheng), he decided to leave a small contingent to watch over Hedong while advancing across the Yellow River into Guanzhong (i.e., the Chang'an region). Once he did, he headed for Chang'an himself, while sending Li Jiancheng to capture the territory around the Tong Pass region to prevent Sui forces at Luoyang from reinforcing Chang'an and Li Shimin north of the Wei River to capture territory there. Meanwhile, Li Shimin's sister Pingyang had also risen in rebellion in support of him, and she was able to gather a sizeable army and capture some cities. She joined forces with Li Shimin and her husband Chai Shao. Soon, Li Yuan reconsolidated his forces and put Chang'an under siege. In winter 617, after defeating a large Sui army, he captured Chang'an from imperial forces and declared Yang You emperor (as Emperor Gong). He had himself made regent (with the title of grand chancellor), Li Shimin made the Duke of Qin, and created the Prince of Tang. Meanwhile, most of the Sui territories and armies did not recognize Emperor Gong as emperor, continuing to support the former Emperor Yang.

Li Yuan's control of the Chang'an region became almost immediately contested by the rebel ruler Xue Ju, the Emperor of Qin, who sent his son Xue Rengao toward Chang'an. Li Yuan sent Li Shimin to resist Xue Rengao, and Li Shimin defeated Xue Rengao at Fufeng (in modern Baoji, Shaanxi), temporarily causing Xue Ju to toy with the idea of surrendering to Li Yuan, although Xue was subsequently dissuaded by his strategist Hao Yuan (郝瑗) from doing so.

In spring 618, with Sui's eastern capital Luoyang (where the officials in charge did not recognize Li Yuan's authorities) under attack by the rebel ruler Li Mi the Duke of Wei, Li Yuan sent Li Jiancheng and Li Shimin to Luoyang, ostensibly to aid the Sui forces at Luoyang but instead intending to test whether Luoyang might submit to him. The officials at Luoyang rebuffed his attempt at rapprochement, and Li Jiancheng and Li Shimin, not wanting to fight either them or Li Mi for control of Luoyang at this stage, withdrew. Li Yuan subsequently changed Li Shimin's title to Duke of Zhao.

In summer 618, when news arrived at Chang'an that Emperor Yang had been killed at Jiangdu in a coup led by the general Yuwen Huaji, Li Yuan had Emperor Gong yield the throne to him, establishing Tang dynasty as its Emperor Gaozu. He created Li Jiancheng crown prince but created Li Shimin the Prince of Qin, also making him Shangshu Ling, the head of the executive bureau of the government (尚書省 Shàngshū Shěng) and a post considered one for a chancellor, while continuing to have Li Shimin serve as a major general as well.

During Emperor Gaozus reign

Campaign to reunify the empire

The first thing that Li Shimin had to deal with was another incursion by Xue Ju, as Xue attacked Jing Prefecture (, roughly modern Pingliang, Gansu) and Emperor Gaozu sent Li Shimin to resist Xue. Li Shimin established his defenses and refused to engage Xue to try to wear Xue Ju out, but at that time, he was afflicted with malaria, and he let his assistants Liu Wenjing and Yin Kaishan take command, ordering them not to engage Xue Ju. Liu and Yin, however, did not take Xue Ju seriously, and Xue Ju ambushed them at Qianshui Plain (, in modern Xianyang), crushing Tang forces and inflicting 50–60% casualties. Li Shimin was forced to withdraw back to Chang'an, and Liu and Yin were removed from their posts. (This would be Li Shimin's only defeat recorded in historical records until the Goguryeo campaign of 645.) Xue Ju, in light of his victory, was ready to launch an assault on Chang'an itself, under Hao Yuan's advice, but suddenly died of an illness in fall 618 and was succeeded by Xue Rengao. Emperor Gaozu then sent Li Shimin against Xue Rengao. Three months after Xue Rengao took the throne, Li Shimin engaged him, and after a fierce battle between Li Shimin and Xue Rengao's major general Zong Luohou, Li Shimin crushed Zong's forces, and then attacked Xue Rengao. Xue Rengao was forced to withdraw into the city of Gaozhi (高墌, in modern Xianyang as well), and once he did, his soldiers began surrendering to Li Shimin en masse. Xue Rengao was himself forced to surrender. Li Shimin had him delivered to Chang'an, where he was executed. Around new year 619, Emperor Gaozu made Li Shimin Taiwei (太尉, one of the Three Excellencies) and put him in charge of Tang operations east of the Tong Pass.

In spring 619, Liu Wuzhou launched a major offensive against Tang. He captured Taiyuan in summer 619, forcing Li Yuanji, who had been in charge there, to flee, and then continued his offensive south. Emperor Gaozu sent Pei Ji against him, but by winter 619, Liu had crushed Pei's forces and taken over nearly all of modern Shanxi. Emperor Gaozu, shocked at the development, considered abandoning the region altogether. Li Shimin opposed doing so and offered to lead the army against Liu. Emperor Gaozu agreed and commissioned him with an army. He crossed the Yellow River and approached Liu's major general Song Jingang but did not engage him, choosing to try to wear Song out, only having his subordinates Yin Kaishan and Qin Shubao engage the other Dingyang generals Yuchi Jingde and Xun Xiang in relatively low-level engagements. Eventually, in spring 620, when Liu and Song ran out of food supplies, they retreated, and Li Shimin gave chase, dealing Song a major defeat. Yuchi and Xun surrendered, and after Li Shimin chased further, both Liu and Song fled to the Eastern Turks. All of Dingyang territory fell into Tang hands.

In summer 620, Emperor Gaozu again commissioned Li Shimin against a major enemy—the former Sui general Wang Shichong, who had Sui's last emperor, Emperor Yang's grandson Yang Tong, yield the throne to him in 619, establishing a new state of Zheng as its emperor. When Li Shimin arrived at the Zheng capital Luoyang, Wang offered peace, but Li Shimin rebuffed him and put Luoyang under siege. Meanwhile, his subordinates took Zheng cities one by one. By winter 620, most of Zheng territory, other than Luoyang and Xiangyang, defended by Wang Shichong's nephew Wang Honglie (王弘烈), had submitted to Tang. Wang sought aid Dou Jiande the Prince of Xia, who controlled most of modern Hebei. Dou, reasoning that if Tang were able to destroy Zheng, his own Xia state would be next, agreed. He sent his official Li Dashi to try to persuade Li Shimin to withdraw, but Li Shimin detained Li Dashi and gave no response. Meanwhile, during the campaign, Li Shimin chose some 1,000 elite soldiers, clad in black uniform and black armor, commanded by himself, to serve as advance troops, with Qin Shubao, Yuchi Jingde, Cheng Zhijie, and Zhai Zhangsun as his assistants.

By spring 621, Luoyang was in desperate situation, and Xia forces had not yet arrived, but Tang troops had also suffered serious casualties, as Luoyang's defenses, aided by powerful bows and catapults, were holding. Emperor Gaozu, hearing that Dou had decided to come to Wang's aid, ordered Li Shimin to withdraw, but Li Shimin sent his secretary Feng Deyi to Chang'an to explain to Emperor Gaozu that if he did withdraw, Wang would recover and again be a major threat in the future. Emperor Gaozu agreed and allowed Li Shimin to continue to siege Luoyang. When Xia forward troops arrived first, Li Shimin surprised and defeated them, and then sent Dou a letter suggesting that he withdraw. Dou would not do so, and, against the advice of his wife Empress Cao and secretary general Ling Jing (凌敬) that he should instead attack Tang's prefectures in modern southern Shanxi, he marched toward Luoyang. Anticipating Dou's maneuver, Li Shimin left a small detachment, commanded by Li Yuanji, at Luoyang, while marching east himself, taking up position at the strategic Hulao Pass. When the armies engaged at Hulao, Li Shimin defeated Dou and captured him. He took Dou back to Luoyang and displayed him to Wang Shichong. Wang, in fear, considered abandoning Luoyang and fleeing south to Xiangyang, but as his generals pointed out that his only hope was Dou, he surrendered. Xia forces, after initially fleeing back to their capital Mingzhou (now Guangfu, Hebei), also surrendered. Zheng and Xia territory were Tang's. Li Shimin returned to Chang'an in a grand victory procession and, to reward Li Shimin, Emperor Gaozu awarded both him and Li Yuanji three mints so that they could mint money of their own. He also bestowed on Li Shimin the special title of "Grand General of Heavenly Strategies" (天策上將 tiāncè shàngjiàng). Meanwhile, Li Shimin's staff, already full of generals and strategists, were supplemented with a number of literary men.

The former Xia territory did not remain in Tang hands for long. In the winter of 621, the Xia general Liu Heita rose against Tang rule, claiming to be avenging Dou, whom Emperor Gaozu had executed against Li Shimin's wishes after he had been brought back to Chang'an. Liu was allied with Xu Yuanlang, a former agrarian rebel general who was nominally under Wang Shichong and who had submitted to Tang after Wang's defeat. Liu dealt successive defeats to Emperor Gaozu's cousin Li Shentong (李神通), the Prince of Huai'an; Li Xiaochang (李孝常), the Prince of Yi'an; and Li Shiji. By the end, he had recovered almost all of the former Xia territory, established his capital at Mingzhou, and proclaimed himself the Prince of Handong. Emperor Gaozu finally sent Li Shimin and Li Yuanji against him in 622 and, after some indecisive battles, Li Shimin defeated him by first erecting a dam across the Ming River and then destroying it, with the resultant flood destroying the rebel army. Liu fled to the Eastern Turks, while Li Shimin then headed east and defeated Xu. After leaving Li Shiji, Li Shentong, and Ren Gui to continue attacking Xu, Li Shimin returned to Chang'an.

Struggle against Li Jiancheng and Li Yuanji

By this point, Li Shimin and his older brother Li Jiancheng, who was created crown prince in 618, reportedly after Emperor Gaozu first offered the position to Li Shimin due to his contributions, were locked in an intense rivalry, as Li Shimin's accomplishments caused people to speculate that he would displace Li Jiancheng as crown prince, and Li Jiancheng, while an accomplished general himself, was overshadowed by his younger brother. The court became divided into a faction favoring the Crown Prince and a faction favoring the Prince of Qin. The rivalry was particularly causing problems within the capital, as the commands of the Crown Prince, the Prince of Qin, and the Prince of Qi Li Yuanji were said to have the same force as the emperor's edicts, and the officials had to carry conflicting orders out by acting on the ones that arrived first. Li Shimin's staff was full of talented men, but Li Jiancheng was supported by Li Yuanji, as well as Emperor Gaozu's concubines, who had better relationships with Li Jiancheng and Li Yuanji than they did with Li Shimin.

Late in 622, when Liu Heita returned east after receiving aid from the Eastern Turks, defeating and killing Li Shimin's cousin Li Daoxuan (李道玄), the Prince of Huaiyang, he again regained most of former Xia territory. Li Jiancheng's staff members Wang Gui and Wei Zheng suggested that Li Jiancheng needed to enhance his own reputation in battle, and so Li Jiancheng volunteered for the mission. Emperor Gaozu thus sent Li Jiancheng, assisted by Li Yuanji, to attack Liu. Li Jiancheng defeated Liu around the new year of 623, and Liu was subsequently betrayed by his own official Zhuge Dewei and delivered to Li Jiancheng. Li Jiancheng executed Liu in his former capital and returned to Chang'an in triumph. China was, by this point, roughly united under Tang rule.

For the next few years, the rivalry intensified, although during the meantime both Li Jiancheng and Li Shimin served as generals when the Eastern Göktürks made incursions. In 623, when the general Fu Gongshi rebelled at Danyang (, in modern Nanjing, Jiangsu), Emperor Gaozu briefly commissioned Li Shimin to attack Fu, but soon cancelled the order and sent Li Shimin's cousin Li Xiaogong the Prince of Zhao Commandery instead.

In 624, when Li Jiancheng was found to have, against regulations, tried to add soldiers to his guard corps, Emperor Gaozu was so angry that he put Li Jiancheng under arrest. In fear, Li Jiancheng's guard commander Yang Wen'gan rebelled. Emperor Gaozu sent Li Shimin against Yang, offering to make him crown prince after he returned. After Li Shimin left, however, Feng Deyi (now a chancellor), Li Yuanji, and the concubines all spoke on Li Jiancheng's behalf, and after Li Shimin returned, Emperor Gaozu did not depose Li Jiancheng, but instead blamed the discord between him and Li Shimin on Li Jiancheng's staff members Wang Gui and Wei Ting and Li Shimin's staff member Du Yan, exiling them to Xi Prefecture (, roughly modern Liangshan Yi Autonomous Prefecture, Sichuan).

Later that year, Emperor Gaozu, troubled by repeated Göktürk incursions, seriously considered burning Chang'an to the ground and moving the capital to Fancheng, a suggestion that Li Jiancheng, Li Yuanji, and Pei Ji agreed with. Li Shimin opposed, however, and the plan was not carried out. Meanwhile, Li Shimin himself was sending his confidants to Luoyang to build up personal control of the army there. After an incident in which Li Shimin suffered a severe case of food poisoning after feasting at Li Jiancheng's palace—an event that both Emperor Gaozu and Li Shimin apparently interpreted as an assassination attempt—Emperor Gaozu considered sending Li Shimin to guard Luoyang to prevent further conflict, but Li Jiancheng and Li Yuanji, after consulting each other, believed that this would only give Li Shimin an opportunity to build up his personal power there, and therefore opposed it. Emperor Gaozu therefore did not carry out the plan. Meanwhile, the rivalry continued. Traditional historical accounts also indicated that at one point, when Li Shimin visited Li Yuanji's mansion, Li Yuanji wanted to assassinate Li Shimin, but Li Jiancheng, who could not resolve to kill a brother, stopped the plot. There was yet another incident in which Li Jiancheng, knowing that a horse threw its rider easily, had Li Shimin ride it, causing Li Shimin to fall off from it several times.

By 626, Li Shimin was fearful that he would be killed by Li Jiancheng, and his staff members Fang Xuanling, Du Ruhui, and Zhangsun Wuji were repeatedly encouraging Li Shimin to attack Li Jiancheng and Li Yuanji first—while Wei Zheng was encouraging Li Jiancheng to attack Li Shimin first. Li Jiancheng persuaded Emperor Gaozu to remove Fang and Du, as well as Li Shimin's trusted guard generals Yuchi Jingde and Cheng Zhijie, from Li Shimin's staff. Zhangsun Wuji, who remained on Li Shimin's staff, continued to try to persuade Li Shimin to attack first.

In summer 626, the Göktürks were making another attack, and under Li Jiancheng's suggestion, Emperor Gaozu, instead of sending Li Shimin to resist the Göktürks as he first was inclined, decided to send Li Yuanji instead. Li Yuanji was given command of much of the army previously under Li Shimin's control, further troubling Li Shimin, who believed that with the army in Li Yuanji's hands, he would be unable to resist an attack. Li Shimin had Yuchi summon Fang and Du back to his mansion secretly, and then on one night submitted an accusation to Emperor Gaozu that Li Jiancheng and Li Yuanji were committing adultery with Emperor Gaozu's concubines. Emperor Gaozu, in response, issued summonses to Li Jiancheng and Li Yuanji for the next morning, convening the senior officials Pei Ji, Xiao Yu, and Chen Shuda to examine Li Shimin's accusations. As Li Jiancheng and Li Yuanji approached the central gate leading to Emperor Gaozu's palace, Xuanwu Gate, Li Shimin carried out the ambush he had set. He personally fired an arrow that killed Li Jiancheng. Subsequently, Yuchi Jingde killed Li Yuanji. Li Shimin's forces entered the palace and, under the intimidation of Li Shimin's forces, Emperor Gaozu agreed to create Li Shimin crown prince. Li Jiancheng's and Li Yuanji's sons were killed, and Li Shimin took Li Yuanji's wife Princess Yang as a concubine. Two months later, with Li Shimin firmly in control of power, Emperor Gaozu yielded the throne to him (as Emperor Taizong).

As emperor

Early reign (626–633)

One of the first actions that Emperor Taizong carried out as emperor was releasing a number of ladies in waiting from the palace and returning them to their homes, so that they could be married. He made his wife Princess Zhangsun the empress, and their oldest son Li Chengqian the crown prince.

Emperor Taizong also immediately faced a crisis, as the Eastern Turkic leader Illig Qaghan (Ashina Duobi), along with his nephew the subordinate Tuli Khan Ashina Shibobi (阿史那什鉢苾), launched a major incursion toward Chang'an, and just 19 days after Emperor Taizong took the throne, the two khans were just across the Wei River from Chang'an. Emperor Taizong, accompanied by Gao Shilian and Fang Xuanling, was forced to meet Ashina Duobi across the river and personally negotiate peace terms, including tributes to Eastern Turks, before Ashina Duobi withdrew.

Late in 626, Emperor Taizong ranked the contributors to Tang rule and granted them titles and fiefs, naming among the first rank of contributors Zhangsun Wuji, Fang Xuanling, Du Ruhui, Yuchi Jingde, and Hou Junji. When Li Shentong, as his distant uncle, objected to being ranked under Fang and Du, Emperor Taizong personally explained how Fang and Du's strategies allowed him to be successful, and this managed to get the other objectors to quiet down, as Emperor Taizong was even willing to rank low such an honored individual as Li Shentong. Emperor Taizong also buried Li Jiancheng and Li Yuanji with honors due imperial princes and had their staff members attend the funeral processions. Meanwhile, he appeared to begin to reshuffle government further—which he had already begun after being created crown prince—by dismissing his father's trusted advisors Xiao Yu and Chen Shuda, making his own trusted advisors chancellors. (Xiao, however, was soon restored to being chancellor, although his career during Emperor Taizong's reign would see repeated dismissals and repeated restorations.) However, he also began to greatly pay attention to the officials' submissions and their criticism of imperial governance, making changes where he saw needed. He also particularly began to trust Wei Zheng, accepting much advice from Wei as far as his personal conduct was concerned. He was also willing to demote his own trusted advisors, as he demoted Gao Shilian after finding that Gao had held back submissions from his deputy Wang Gui. Viewing Sui's Emperor Yang as a negative example, he frequently solicited criticism, rewarding those officials willing to offer them, particularly Wei and Wang Gui. His openness to opposing ideas was also evident in his attempt to reconcile traditional Taoist religion and Buddhism, as demonstrated in his ''Emperor's Preface to the Sacred Teachings'', and Emperor Taizong was at least a nominal Taoist.

Li Yis Rebellion

Also in 627, the general Li Yi the Prince of Yan—a late-Sui warlord who later submitted to Tang, who associated with Li Jiancheng—fearing that Emperor Taizong would eventually take action against him, rebelled at Bin Prefecture (豳州, in modern Xianyang), but was quickly crushed by the official Yang Ji and killed in flight. Later that year, when Emperor Gaozu's cousin Li Youliang (李幼良) the Prince of Changle, the commandant at Liang Prefecture (, roughly modern Wuwei, Gansu), was accused of allowing his staff to oppress the people and to trade with Qiang and Xiongnu tribesmen, Emperor Taizong sent the chancellor Yuwen Shiji (Yuwen Huaji's brother) to investigate, and in fear, Li Youliang's staff members plotted to hold him hostage and rebel. When this was discovered, Emperor Taizong forced Li Youliang to commit suicide. Late in the year, Wang Junkuo (王君廓), the commandant at You Prefecture (幽州, roughly modern Beijing), also rebelled, but was defeated quickly and killed in flight. However, although there were also reports that Feng Ang, a warlord in the Lingnan region, was rebelling, Emperor Taizong, at Wei's suggestion, sent messengers to comfort Feng, and Feng submitted.

Also in 627, Emperor Taizong, seeing that there were too many prefectures and counties, consolidated and merged many of them, and further created another level of local political organization above prefectures—the circuit (道 dào)—dividing his state into 10 circuits.

Campaign against the Eastern Turks

In 628, with Ashina Duobi and Ashina Shibobi having a falling out, Ashina Shibobi submitted to Emperor Taizong, as did the chieftains of Khitan tribes, who had previously submitted to the Eastern Turks. With their khaganate in turmoil, Ashina Duobi was no longer able to protect the last late-Sui rebel ruler who alone remained standing against Tang pressure—Liang Shidu the Emperor of Liang, and in summer 628, with the Tang generals Chai Shao and Xue Wanjun sieging the Liang capital Shuofang (in modern Yulin, Shaanxi), Liang Shidu's cousin Liang Luoren (梁洛仁) killed Liang Shidu and surrendered, finally uniting China. With the Eastern Turkic Khaganate weakened, their vassal Xueyantuo also broke away and formed its own khanate, and Emperor Taizong entered into an alliance with Xueyantuo's leader Yinan, creating Yinan the Zhenzhupiqie Khan (or Zhenzhu Khan in short).

In late 629, believing the time ripe for a major attack on the Eastern Turks, Emperor Taizong commissioned the general Li Jing with overall command of a multi-pronged army, assisted by the generals Li Shiji, Li Daozong, Chai Shao, Xue Wanche (, Xue Wanjun's brother) and Su Dingfang, attacking the Eastern Turks at multiple points. The army was successful in its attacks, forcing Ashina Duobi to flee, and by late spring 630, Ashina Duobi had been captured, and Eastern-Turkic chieftains all submitted to Tang. Emperor Taizong spared Ashina Duobi but detained him at Chang'an, and he considered what to do with the Eastern Turks.

The main opposing views were from the chancellors Wen Yanbo (who advocated leaving the Turks within China's borders to serve as a defense perimeter) and Wei (who advocated leaving them outside the borders). Emperor Taizong accepted Wen's suggestion and established a number of prefectures to accommodate the Turks, leaving them governed by their chieftains without creating a new khan to govern them.

In 631, Emperor Taizong established a feudal scheme, where the contributors to his reign were given, in addition to their current posts, additional posts as prefectural governors, to be passed on to their descendants. Soon, however, receiving much opposition to the plan, the strongest of which came from Zhangsun Wuji, Emperor Taizong cancelled the scheme.

After the conquest of the Eastern Turkic Khaganate, Emperor Taizong's officials repeatedly requested that he carry out sacrifices to heaven and earth at Mount Tai, and Emperor Taizong, while at times tempted by the proposal, was repeatedly dissuaded from doing so by Wei, who pointed out the expenses and the labors that would be imposed on the people as a result, and also that this would open China's borders to attack.

Middle reign (634–641)

In 634, Emperor Taizong sent 13 high level officials, including Li Jing and Xiao Yu, to examine the circuits to see whether the local officials were capable, to find out whether the people were suffering, to comfort the poor, and to select capable people to serve in civil service. (Li Jing initially recommended Wei Zheng, but Emperor Taizong declined sending Wei, stating that Wei needed to stay to point out his faults and that he could not afford to have Wei away even for a single day.)

Campaign against Tuyuhun

Around this time, Tang was having increasing conflicts with Tuyuhun, whose Busabo Khan Murong Fuyun, under instigation by his strategist the Prince of Tianzhu, had been repeatedly attacking Tang prefectures on the borders. At one point, Murong Fuyun sought to have a Tang princess marry his son the Prince of Zun, but the marriage negotiations broke down over Emperor Taizong's insistence that the Prince of Zun come to Chang'an for the wedding. In summer 634, Emperor Taizong had the generals Duan Zhixuan and Fan Xing lead forces against Tuyuhun, but with Tuyuhun's forces highly mobile and avoiding direct confrontation, Duan, while not defeated, could not make major gains. Once Duan withdrew, Tuyuhun resumed hostilities. In winter 634, with the Tibetan king Songtsän Gampo making overtures to marry a Tang princess as well, Emperor Taizong sent the emissary Feng Dexia to Tibet with an eye toward an alliance against Tuyuhun. In winter 634, he commissioned Li Jing, assisted by the other generals Hou Junji, Xue Wanjun, Xue Wanche, Qibi Heli, Li Daozong, Li Daliang, Li Daoyan, and Gao Zengsheng (高甑生), to attack Tuyuhun. In 635, Li Jing's forces crushed Tuyuhun forces. Murong Fuyun was killed by his own subordinates, and his son Murong Shun killed the Prince of Tianzhu and surrendered. Emperor Taizong created Murong Shun the new khan, although Murong Shun was soon assassinated. Emperor Taizong then created Murong Shun's son Murong Nuohebo as the new khan.

Also in 635, Emperor Gaozu died, and Emperor Taizong, observing a mourning period, briefly had Li Chengqian serve as regent, and after he resumed his authorities less than two months later, he still authorized Li Chengqian to thereafter rule on minor matters.

In spring 636, Emperor Taizong commissioned his brothers and sons as commandants and changed their titles in accordance with the commands that they received, sending them to their posts—with the exception of his son Li Tai the Prince of Wei, who by this point was beginning to be highly favored by him. He further allowed Li Tai to engage literary men to serve as his assistants, as Li Tai favored literature. From this point on, Li Tai would be so favored that there began to be talks that Emperor Taizong might let him displace Li Chengqian, whose favors began to wane.

In fall 636, Empress Zhangsun died. Emperor Taizong mourned her bitterly and personally wrote the text of her monument.

In summer 637, Emperor Taizong recreated the feudal scheme that he had considered and abandoned in 631, creating 35 hereditary prefect posts. (By 639, however, the system was again abandoned after much opposition.)

Treatment of Noble Clans

Sometime before 638, Emperor Taizong, disgusted with the traditional noble clans of Cui, Lu, Li, and Zheng and believing that they were abusing their highly honored names, commissioned Gao Shilian, Wei Ting, Linghu Defen, and Cen Wenben to compile a work later to be known as the Records of Clans (氏族志), with the intent of dividing the clans into nine classes based on their past contributions, good deeds, and ill deeds. In an initial draft that Gao submitted, he nevertheless ranked the branch of the Cui clan that the official Cui Min'gan belonged to as the highest, a decision that Emperor Taizong rebuked, as he pointed out that Gao was merely again looking at tradition and not the recent contributions. He therefore personally intervened in revising the work, reducing Cui's clan to the third class.

Tibetan attack on Songzhou

In fall 638, Tibet's Songtsän Gampo, displeased that Emperor Taizong had declined to give him a Tang princess in marriage and believing that Murong Nuohebo had persuaded Emperor Taizong to decline the marriage proposal, launched a major attack with forces of 200,000 on Tuyuhun and then on several Tang prefectures, putting Song Prefecture (松州, roughly modern Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan) under siege. Emperor Taizong commissioned Hou Junji, assisted by Zhishi Sili, Niu Jinda, and Liu Jian, of a total of force of 50,000 to counterattack, and Niu, who commanded the forward forces, defeated Tibetan forces at Song Prefecture. Songsän Gampo withdrew and sued for peace, but still sought to marry a Tang princess. Emperor Taizong agreed this time.

Also in 638, believing that Xueyantuo was growing increasingly strong and difficult to control, Emperor Taizong granted Yinan's sons Bazhuo and Jialibi both lesser khan titles, to try to create dissensions between them.

In summer 639, Ashina Jiesheshuai, the younger brother of Ashina Shibobi, whom Emperor Taizong did not favor and gave little recognition to, formed a conspiracy with Ashina Shibobi's son Ashina Hexiangu to assassinate Emperor Taizong. They had planned to wait for Li Zhi the Prince of Jin to depart from the palace in the morning and use that opportunity to attack the palace. On the day they planned, however, Li Zhi did not leave the palace, and Ashina Jiesheshuai attacked anyway but was quickly defeated, captured, and executed. After this incident, however, the officials began advocating sending the Turks away from the heart of the state. In fall 639, Emperor Taizong created a Turkish prince who had served him faithfully, Li Simo (né Ashina Simo) as the khan of a newly recreated Eastern Turkic state (as Qilibi Khan), giving him all of the Turks and Xiongnu who had surrendered as his subordinates, to be settled north of the Great Wall and the Yellow River. However, the Turks were fearful of Xueyantuo and initially refused to head to their new location. Emperor Taizong issued an edict to Yinan that he and Li Simo keep their peace and not attack each other, and after receiving from Yinan the assurance that he would not attack, the Turks advanced to the new location.

Campaign against Western Turks

Taizong began a series of campaigns against the Western Turks (Xitujue) and their allies, the oasis states of the Tarim Basin, around 640. These hostilities between the Western Turks and Tang would continue until the defeat and conquest of the Western Turks in 657 under Taizong's successor, Gaozong. The kingdoms of Shule and Khotan surrendered to the Chinese in 632, as did the kingdom of Yarkand in 635. Qu Wentai (麴文泰), the king of Gaochang, who had previously been submissive to Tang, had become increasingly hostile to Tang, allying with the Western Turks. In 640, Emperor Taizong commissioned Hou Junji, assisted by Xue Wanjun, to launch a major attack on Gaochang. As they approached Gaochang, Qu Wentai died in fear and was succeeded by his son Qu Zhisheng (麴智盛). Qu Zhisheng offered to submit, but Hou demanded a surrender, which Qu Zhisheng refused. However, Hou put Gaochang under siege, and with aid from the Western Turks not arriving, Qu Zhisheng surrendered. Wei Zheng suggested that Emperor Taizong allow Qu Zhisheng to remain king, pointing out that the monetary and human costs would be high to keep a permanent garrison at Gaochang, but Emperor Taizong disagreed, and he converted Gaochang into two prefectures and annexed it into his state.

In winter 640, Songsän Gampo sent his prime minister Gar Tongtsen Yülsung ("Lu Dongzan" in Chinese) as an emissary to Tang, offering tributes and again requesting marriage. Emperor Taizong created a daughter of a clansman as the Princess Wencheng, and in 641 sent Li Daozong to accompany Princess Wencheng to Tibet to preside over the wedding.

In winter 641, believing that Emperor Taizong was about to carry out sacrifices to heaven and earth at Mount Tai and would be unable to aid the Eastern Turks, Yinan launched a major attack on them, commanded by his son Dadu (大度). Li Simo was forced to retreat inside the Great Wall. Emperor Taizong commissioned Li Shiji, assisted by Zhang Jian, Li Daliang, Zhang Shigui, and Li Xiyu, to attack Xueyantuo. Li Shiji soon defeated Dadu at Nuozhen River (, flowing through modern Baotou, Inner Mongolia), and Dadu fled.

Late reign (642–649)

By 642, it was clear that Li Tai had ambitions on replacing his brother Li Chengqian, and the governmental officials began to be divided into pro-Li Chengqian and pro-Li Tai factions. After urging by Wei Zheng and Chu Suiliang to take actions that would clarify that Li Chengqian's position was secure, Emperor Taizong attempted to do so by making repeated statements to that effect, but his continued favoring of Li Tai led to continued speculation among officials.

Also by 642, Xueyantuo had posed a sufficiently serious threat (albeit still formally submissive) that Emperor Taizong saw two alternatives—destroying it by force or forming into a heqin relationship by marrying one of his daughters to Yinan. This particularly became an issue after the Tang general Qibi Heli (契苾何力), the chieftain of the Qibi Tribe, was kidnapped by his own subordinates and taken to Xueyantuo. In order to ransom Qibi, Emperor Taizong made a promise to eventually give his daughter Princess Xinxing to Yinan in marriage, and Yinan released Qibi.

In the winter 642, an event took place in Goguryeo that would eventually precipitate wars between Tang and Goguryeo. According to Chinese accounts King Yeongnyu, the king of Goguryeo, was apprehensive about his general Yŏn Kaesomun and was plotting with his other officials to kill Yeon. When Yŏn received the news, he started a coup and killed the king and the high level officials. He declared King Yeongnyu's nephew Ko Chang (King Bojang) king, while taking power himself with the title of Dae Mangniji (, Generalissimo). When Emperor Taizong received the news, there were suggestions that an attack be launched against Goguryeo, suggestions that Emperor Taizong initially declined.

In spring 643, Wei died, and Emperor Taizong mourned him bitterly, authoring Wei's monument himself and, prior to Wei's death, promising to give his daughter Princess Hengshan in marriage to Wei's son Wei Shuyu (魏叔玉). Later in spring, Emperor Taizong commissioned 24 portraits at Lingyan Pavilion to commemorate the 24 great contributors to his reign.

Contacts with the Byzantine Empire

The Old Book of Tang and New Book of Tang mention several embassies made by Fu lin (; i.e. the Byzantine Empire), which they equated with Daqin (which may refer to the Roman Empire or Middle East), beginning in 643 with an embassy sent by the king Boduoli (波多力, i.e. Constans II Pogonatos) to Emperor Taizong, bearing gifts such as red glass and green gemstones. These histories also provided cursory descriptions of Constantinople and its walls, as well as how it was besieged by Da shi (大食; the Arabs of the Umayyad Caliphate) and their commander "Mo-yi" (摩拽; i.e. Muawiyah I, governor of Syria before becoming caliph), who forced the Byzantines to pay tribute. Henry Yule highlights the fact that Yazdegerd III (r. 632–651), last ruler of the Sasanian Empire, sent diplomats to China for securing aid from Emperor Taizong (considered the suzerain over Ferghana in Central Asia) during the loss of the Persian heartland to the Islamic Rashidun Caliphate, which may have also prompted the Byzantines to send envoys to China amid their recent loss of Syria to the Muslims. Tang Chinese sources also recorded how Sassanid prince Peroz III (636–679) fled to Tang China following the conquest of Persia by the growing Islamic caliphate.

The expansion of China's power into Central Asia under Emperor Taizong seems to have been noticed in the West. Theophylact Simocatta, a Byzantine Greek historian during the reign of Heraclius (r. 610–641), wrote that Taugast (or Taugas; Old Turkic: Tabghach, from Tuoba, the Xianbei clan of Northern Wei), was a great eastern empire in the Far East that ruled over Turkic people, with a capital city roughly 1,500 miles northeast from India that he called Khubdan (from the Turkic word Khumdan, meaning, Chang'an), where idolatry was practiced but the people were wise and lived by just laws. He depicted the Chinese empire as being divided by a great river (i.e. the Yangzi) that served as the boundary between two rival states at war, yet during the reign of Byzantine Emperor Maurice (582–602 CE) the northerners wearing "black coats" conquered the "red coats" of the south (black being a distinctive color worn by the people of Shaanxi, location of the Sui capital Sui Chang'an, according to the 16th-century Persian traveler Hajji Mahomed, or Chaggi Memet). This account may correspond to the conquest of the Chen dynasty and reunification of China by Emperor Wen of Sui (r. 581–604). Simocatta names their ruler as Taisson, which he claimed meant Son of God, either correlating to the Chinese Tianzi (i.e. Son of Heaven) or even the name of the contemporary ruler Emperor Taizong.

Succession dispute

Also in 643, Emperor Taizong would see major turmoil among his own closest family. In spring 643, his son Li You (李祐) the Prince of Qi, angry over restrictions that his secretary general Quan Wanji had often placed on him, killed Quan and declared a rebellion. Emperor Taizong sent Li Shiji against Li You, but before Li Shiji could engage Li You, Li You was captured by his own subordinate Du Xingmin (杜行敏) and delivered to Chang'an, where Emperor Taizong ordered him to commit suicide and executed 44 of his associates.

The death of Li You drew out news of another plot. Li Chengqian, who had been fearful that Emperor Taizong would eventually remove him and replace him with Li Tai, had begun to conspire with Hou Junji, Li Yuanchang (李元昌) the Prince of Han (Emperor Taizong's brother), the general Li Anyan, and his brothers-in-law Zhao Jie and Du He (杜荷, Du Ruhui's son) to overthrow Emperor Taizong. During the investigations in the aftermaths of Li You's rebellion, one of the co-conspirators, Li Chengqian's guard Gegan Chengji, was implicated by association, and in order to save himself, he revealed Li Chengqian's plot. Emperor Taizong was shocked by the news, and he appointed Zhangsun Wuji, Fang Xuanling, Xiao Yu, and Li Shiji, along with the officials in charge of the supreme court and the legislative and examination bureaus of the government to carry out a joint investigation. At the suggestion of the mid-level official Lai Ji, Emperor Taizong deposed, but did not kill, Li Chengqian, while ordering Li Yuanchang to commit suicide and executing Hou Junji, Li Anyan, Zhao, and Du.

Taizong's eldest son Li Chengqian chose to speak Turkic, dress in Turkic clothes and even set up a tent in his residence in imitation of a Turkic khan. Taizong removed him from the position of heir apparent and chose as his successor Li Zhi, who embraced Han Chinese cultural heritage.

After Li Chengqian was deposed, Emperor Taizong briefly promised Li Tai that he would be made crown prince. However, as the investigations continued, Emperor Taizong came to the belief that Li Chengqian's downfall was driven by Li Tai's machinations, and therefore resolved to depose Li Tai as well. At Zhangsun's suggestion, Emperor Taizong had a younger son, Li Zhi the Prince of Jin (who, like Li Chengqian and Li Tai, were born of Empress Zhangsun), crown prince, who was considered kinder and gentler, while exiling Li Chengqian and Li Tai. However, starting later that year, Emperor Taizong began to doubt whether Li Zhi's personality was sufficiently strong to serve as emperor, and he toyed with the idea of making another son, Li Ke the Prince of Wu, a son of his concubine Consort Yang (Emperor Yang of Sui's daughter), crown prince, but did not do so due to strong opposition by Zhangsun Wuji.

Meanwhile, coming to the belief that he made an ill-advised promise to Yinan to give him Princess Xinxing in marriage, Emperor Taizong demanded a large amount of bride price – 50,000 horses, 10,000 cows and camels, and 100,000 sheep—a price that Yinan agreed to, but could not immediately collect and deliver. Emperor Taizong used it as an excuse to cancel the marriage agreement. Meanwhile, as Wei Zheng had, prior to his death, recommended Hou Junji and Li Chengqian's staff member Du Zhenglun as chancellors, Emperor Taizong came to suspect that Wei was part of the plot as well. He destroyed the monument he had authored for Wei and cancelled the betrothal between Wei Shuyu and Princess Hengshan.

Campaign against the Karasahr

In 644, with Yanqi's king Long Tuqizhi, who had assisted the Tang campaign to conquer Gaochang, turning against Tang and allying with the Western Turks, Emperor Taizong sent the general Guo Xiaoke (郭孝恪), the commandant at Anxi (安西, i.e., Gaochang) to launch a surprise attack on Yanqi. Guo caught Long Tuqizhi by surprise and captured him, making his brother Long Lipozhun regent. (The Western Turkic viceroy Ashina Quli (阿史那屈利) subsequently captured Long Lipozhun and briefly occupied Yanqi, although he then, not wanting a direct confrontation with Tang, withdrew, and the Yanqi nobles made Long Tuqizhi's cousin Long Xuepoanazhi king.)

Goguryeo-Tang War

Also in 644, with Goguryeo attacking Silla and Silla requesting aid, Emperor Taizong decided to prepare for a campaign to conquer Goguryeo. He arrested the emissaries that Yŏn sent to the Tang court, accusing them of disloyalty to King Yeongnyu. By winter 644, the mobilization was in full force. (Apparently because of Tang's preparation to attack Goguryeo, however, the reconstituted Eastern Turkic people, fearing an attack from Xueyantuo at a time that Tang would be ill-equipped to assist, panicked and abandoned their khan Li Simo, fleeing into Tang territory. Emperor Taizong reabsorbed the Eastern Turks into Tang, while making Li Simo a general in his army.)

In spring 645, Emperor Taizong departed from Luoyang and led the troops northeast, behind a vanguard of 60,000 commanded by Li Shiji and Li Daozong. At the same time, Zhang Liang led the other 40,000 from sea. By summer 645, Tang forces had captured Yodong Fortress (, in modern Liaoyang, Liaoning), and headed southeast toward the Goguryeo capital Pyongyang. Emperor Taizong personally led about 30,000 Tang and tribal forces and defeated a 150,000 force commanded by two Gogureyo generals and then put Ansi (安市, in modern Anshan, Liaoning) fortress under siege.

However, the capable defense put up by Ansi's commanding general stymied Tang forces and, in late fall, after suffering some casualties, with winter fast approaching and his food supplies running out, Emperor Taizong withdrew. He much regretted launching the campaign and made the comment, "If Wei Zheng were still alive, he would never have let me launch this campaign." He reerected the monument he authored for Wei and summoned Wei's wife and children to meet him, treating them well.

Campaign against Xueyantuo and conquest of the Kucha

Meanwhile, in the aftermaths of the Goguryeo campaign, Xueyantuo's Duomi Khan Bazhuo (son of Yinan, who had died earlier in 645) launched attacks against Tang's border prefectures, with largely inconclusive results. In spring 646, the Tang generals Qiao Shiwang and Zhishi Sili counterattacked, defeating Bazhuo's forces, causing him to flee. His vassals Huige, Pugu (僕骨), and Tongluo tribes took the opportunity to rebel and attack him. Hearing this, Emperor Taizong launched a major attack, commanded by Li Daozong, Ashina She'er, Zhishi Sili, Qibi Heli, Xue Wanche, and Zhang Jian, against Xueyantuo. With Xueyantuo under attack from multiple sides, Bazhuo was killed by Huige forces, and the remaining Xueyantuo people fled and supported Bazhuo's cousin Duomozhi as Yitewushi Khan, but soon offered to submit to Tang. Emperor Taizong sent Li Shiji toward Duomozhi's location, with the direction to either accept his submission or destroy him. Duomozhi surrendered and was taken to Chang'an, ending Xueyantuo's rule over the region. The other tribes formerly submissive to Xueyantuo offered Emperor Taizong the title of "Heavenly Khan" and thereafter largely became submissive to Tang. Tang nominally established seven command posts and six prefectures over the region. (Huige's khan Yaoluoge Tumidu, while submissive to Tang, for some time tried to take control over the region himself, but was subsequently assassinated in 648, and there would be no other organized attempt by Huige to take over the region until for about another century.)

After the victory over Xueyantuo, Emperor Taizong again turned his attention toward to Goguryeo, cutting off relations once more and considering another campaign. Under suggestions by some of his officials, he decided to launch harassment campaigns against Goguryeo's northern region on a yearly basis, to weaken Goguryeo gradually. The first of these campaigns was launched in spring 647, with Li Shiji and Niu Jinda in command, and would reoccur. All this was in preparation of another campaign in 649 with forces totaling 300,000, but Taizong died before this campaign and the campaign was stalled into Gaozong's reign.

In 648, Emperor Taizong launched another campaign, commanded by Ashina She'er, aimed at Qiuzi, but first attacking Yanqi and killing Long Xuepoanazhi and replacing him with his cousin Long Xiannazhun. Ashina She'er advanced on Qiuzi and captured its king Bai Helibushibi, making his brother king instead.

Death

By summer of 649, Emperor Taizong was seriously ill—with some believing that his illness was caused by the medicine he was administered by Buddhists or his taking of pills given to him by alchemists. Believing Li Shiji to be capable but fearing that he would not be submissive to Li Zhi, he demoted Li Shiji out of the capital to be the commandant at remote Die Prefecture (疊州, roughly modern Gannan Tibetan Autonomous Prefecture, Gansu), with instructions to Li Zhi that if Li Shiji hesitated, to execute him immediately, and if he did not, to recall him after Emperor Taizong's death and make him chancellor. Li Shiji, when receiving the order and realizing that his life was at stake, immediately departed for Die Prefecture. (After Emperor Taizong's death, Li Zhi would indeed recall Li Shiji and make him chancellor.) Soon thereafter, Emperor Taizong, after entrusting Li Zhi to Zhangsun Wuji and Chu Suiliang, died at his summer palace Cuiwei Palace. His death was initially kept a secret, and three days later, after his casket had been returned to Chang'an, his death was announced, and Li Zhi took the throne as Emperor Gaozong.

Religious views

Emperor Taizong stated he believed in the Tao, although his vision of it was a greatly syncretized version. He promoted religious tolerance and incorporated elements of Taoism, Confucianism, and Buddhism in his personal beliefs, while allowing the presence of Zoroastrianism, Judaism, Islam, Syriac Christianity (including the Church of the East), and other Middle Eastern religions within the empire.

Monuments

After consolidating the Tang Empire, Emperor Taizong ordered six large stone panels, known as Zhaoling Liujun, to be carved with the portraits of his favorite horses. These were the horses he had ridden in overcoming his rivals and securing the borders of the country.

Emperor Taizong further composed laudatory poems for each of the six horses depicted in the stone reliefs. Constructed between 636 and 649 CE, the stone reliefs "exemplify the beauty of early Tang sculpture; the images are realistic yet powerful, created with simplicity and matured craftsmanship."

After Taizong's death, the monuments were situated along the east and west sides of the "spirit path" at the North Gate of the tomb complex named Zhaoling or Zhao Mausoleum. The six stone horse reliefs remained at the Mausoleum until the early twentieth century, when four were removed to the Beilin Museum in Xi'an, China, and two were sold and subsequently donated to the Penn Museum in Philadelphia in 1921.

Era name

• Zhenguan (貞觀 zhēnguàn ) 627–649

Chancellors during reign

Consorts and issue

• Empress Wende, of the Zhangsun clan of Henan (文德皇后 河南長孫氏／河南长孙氏; 601–636)

　• Li Chengqian, Prince Min of Hengshan (恆山愍王／恒山愍王 李承亁; 618–645), 1st son

　• Li Tai, Prince Gong of Pu (濮恭王 李泰; 620–653), 4th son

　• Princess Changle (長樂公主／长乐公主; 621–643), personal name Lizhi (麗質／丽质), 5th daughter

　　• Married Zhangsun Chong of Henan (河南 長孫衝／长孙冲), eldest son of Zhangsun Wuji, in 633, and had issue (one son)

　• Li Zhi, Emperor Gaozong (高宗 李治; 628–683), 9th son

　• Princess Chengyang (城陽公主／城阳公主; d. 671), 16th daughter

　　• Married Du He of Jingzhao, Duke of Xiangyang Commandery (襄陽郡公／襄阳郡公 京兆 杜荷; 616–643), second son of Du Ruhui

　　• Married Xue Guan of Hedong, Marquis of Hedong County (河東縣開國侯 河東 薛瓘／河东县开国侯 河东 薛瓘), in 643, and had issue (two sons)

　• Princess Jinyang (晉陽公主／晋阳公主; 633–644), courtesy name Mingda (明達／明达), 19th daughter

　• Princess Xincheng (新城公主; 634–663), 21st daughter

　　• Married Zhangsun Quan of Henan (河南 長孫詮／长孙诠; 636–659) in 649

　　• Married Wei Zhengju of Jingzhao (京兆 韋正矩／韦正矩; d. 663) in 660

• Noble Consort, of the Wei clan of Jingzhao (貴妃 京兆韋氏／贵妃 京兆韦氏; 597–665), personal name Gui (珪)

　• Princess Linchuan (臨川公主／临川公主; 624–682), courtesy name Mengjiang (孟薑／孟姜), 10th daughter

　　• Married Zhou Daowu of Runan, Duke of Qiao Commandery (諫郡公 汝南 周道務／谯郡公 汝南 周道务), and had issue (three sons, two daughters)

　• Li Shen, Prince of Ji (紀王 李慎／纪王 李慎; d. 689), 10th son

• Noble Consort, of the Yang clan (貴妃 楊氏／贵妃 杨氏)

　• Li Fu, Prince of Zhao (趙王 李福／赵王 李福; 634–670), 13th son

• Consort, of the Yang clan (妃 楊氏／杨氏)

　• Li Ke, Prince of Wu (吳王／吴王 李恪; 619–653), 3rd son

　• Li Yin, Prince Dao of Shu (蜀悼王 李愔; d. 667), 6th son

• Consort, of the Yin clan (妃 陰氏/阴氏)

　• Li You, Prince of Qi (齊王／齐王 李佑; –643), 5th son

• Virtuous Consort, of the Yan clan (德妃 燕氏; 609–671)

　• Li Zhen, Prince Jing of Yue (越敬王 李貞／李贞; 627–688), 8th son

　• Li Xiao, Prince Shang of Jiang (江殤王 李囂／江殇王 李嚣; d. 632), 11th son

• Able Consort, of the Zheng clan (賢妃／贤妃 郑氏)

• Able Consort, of the Xu clan (賢妃／贤妃 徐氏; 627–650), personal name Hui (惠)

• Lady of Bright Countenance, of the Wei clan (昭容 韋氏／韦氏), personal name Nizi (尼子)

• Concubine, of a certain clan (下嬪／下嫔 某氏)

　• Princess Yuzhang (豫章公主), 6th daughter

　　• Married Tang Yishi (唐義識／唐义识), son of Tang Jian, in 637, and had issue (one son)

• Lady of Beauty, of the Xiao clan (美人 蕭氏／萧氏)

• Lady of Talent, of the Wu clan (才人 武氏; 624–705), commonly known as Wu Zetian

• Lady of Talent, of the Cui clan of Qinghe (才人 清河崔氏)

• Lady of Talent, of the Xiao clan (才人 蕭氏／萧氏)

• Princess Consort, of the Yang clan of Hongnong (王妃 弘農楊氏／弘农杨氏)

　• Li Ming, Prince Gong of Cao (曹恭王 李明; d. 682), 14th son

• Lady, of the Wang clan (王氏)

　• Li Yun, Prince of Jiang (蔣王 李惲／蒋王 李恽; d. 674), 7th son

• Lady, of the Gao clan (高氏)

• Unknown

　• Li Kuan, Prince of Chu (楚王 李寬／李宽; b. 619), 2nd son

　• Li Jian, Prince of Dai (代王 李簡／李简; 631), 12th son

　• Princess Xiangcheng (襄城公主; d. 651), 1st daughter

　　• Married Xiao Rui of Lanling, Duke of Song (宋國公 蘭陵 蕭銳／宋国公 兰陵 箫锐), eldest son of Xiao Yu

　• Princess Runan (汝南公主; d. 636), 2nd daughter

　• Princess Nanping (南平公主; d. 650), 3rd daughter

　　• Married Wang Jingzhi, Baron of Nancheng County (南城縣男／南城县男 王敬直), youngest son of Wang Gui, in 637

　　• Married Liu Xuanyi of Henan, Duke of Yu (渝國公 河南 劉玄意／渝国公 河南 刘玄意), eldest son of Liu Zhenghui, in 643

　• Princess Sui'an (遂安公主; d. 651), 4th daughter

　　• Married Dou Kui of Henan, Baron of Xindou County (信都縣男 河南 竇逵／信都县男 河南 窦逵), grandson of Dou Kang, and had issue (one son)

　　• Married Wang Dali of Henan (河南 王大禮／王大礼; 613–669), and had issue (two sons)

　• Princess Baling (巴陵公主; d. 653), 7th daughter

　　• Married Chai Lingwu, Duke of Xiangyang Commandery (襄陽郡公／襄阳郡公 柴令武; d. 653), second son of Chai Shao

　• Princess Pu'an (普安公主), 8th daughter

　　• Married Shi Renbiao, Duke of Dou (竇國公／窦国公 史仁表), eldest son of Shi Danai

　• Princess Dongyang (東陽公主／东阳公主; d. 701), 9th daughter

　　• Married Gao Luxing of Bohai, Duke of Shen (申國公／申国公 渤海 高履行), eldest son of Gao Shilian

　• Princess Qinghe (清河公主; 624–664), personal name Jing (敬), courtesy name Dexian (德賢／德贤), 11th daughter

　　• Married Cheng Huailiang, Duke of Dong'a County (東阿縣公 程懷亮／东阿县公 程怀亮), second son of Cheng Zhijie, in 633

　• Princess Lanling (蘭陵公主／兰陵公主; 628–659), personal name Shu (淑), courtesy name Lizhen (丽贞／麗貞), 19th daughter

　　• Married Dou Huaizhe of Henan (河南 竇懷悊／窦怀哲), in 636, and had issue (one daughter)

　• Princess Jin'an (晉安公主／晋安公主), 13th daughter

　　• Married Wei Si'an of Jingzhao (京兆 韋思安／韦思安)

　　• Married Yang Renlu of Hongnong (弘農 楊仁輅／弘农 杨仁辂)

　• Princess Ankang (安康公主), 14th daughter

　　• Married Dugu Chen of Henan (河南 獨孤諶／独孤谌), in 643

　• Princess Xinxing (新興公主/新兴公主), 15th daughter

　　• Married Zhangsun Xi of Henan (河南 長孫曦／长孙曦)

　• Princess Gaoyang (高陽公主／高阳公主; d. 653), 17th daughter

　　• Married Fang Yi'ai of Qinghe (清河 房遺愛／房遗爱; d. 653), second son of Fang Xuanling, in 648

　• Princess Jinshan (金山公主), 18th daughter

　• Princess Changshan (常山公主), 20th daughter

　• Princess of Dingxiang County (定襄縣主／定襄县主; 610–653), stepdaughter

　　• Married Ashina Zhong, Duke of Xue (薛國公／薛国公 阿史那忠; 611–675)

Literary and other cultural references

• Emperor Taizong was the subject of a 64-chapter (in eight volumes) The Novel of the Prince of Qin of the Great Tang (大唐秦王詞話 Datang Qin Wang Cihua) by Zhu Shenglin of the Ming dynasty. The novel is also known as The Biography of the Prince of Qin of the Tang Dynasty (唐秦王本傳), Romance of Tang (唐傳演義), and Romance of the Prince of Qin (秦王演義).

• Journey to the West details a fictional account of the origin of the Chinese door gods. Emperor Taizong asked his generals Qin Shubao and Yuchi Gong to stand guard outside his bedroom to protect him from a vengeful spirit.

Television/Cinema

• Hong Kong's TVB produced a television series about Li Shimin's adventure based on The Novel of the Prince of Qin of the Great Tang.

• The Foundation, a 1983 Hong Kong television series produced by TVB. It featured a young Li Shimin prominently as one of its three leading characters.

• Portrayed by Sean Lau in the 1987 TVB TV series The Grand Canal.

• Portrayed by Wilson Lam in 1993 Taiwan's TTV 54 episodes TV series Tang Taizong, Li Shimin.

• Portrayed by Peter Ho in the 2004 TV series The Prince of Qin, Li Shimin.

• Portrayed by Shen Xiaohai in the 2006 TV series Initiating Prosperity.

• Portrayed by Tang Guoqiang in the CCTV-1 TV series Carol of Zhenguan.

• Portrayed by Ma Yue in the 2006 BTV TV series The Rise of the Tang Empire.

• Portrayed by Seo In-seok and Lee Joo-hyeon in 2006–2007 SBS TV series Yeon Gaesomun.

• Portrayed by Song Yong-tae in the 2006–2007 KBS TV series Dae Jo Yeong.

• Portrayed by Yu Shaoqun in the 2012 Hunan TV TV series Heroes of Sui and Tang Dynasties.

• Portrayed by Yoon Seung-won in the 2012–2013 KBS1 TV series Dream of the Emperor.

• Portrayed by Du Chun in the 2013 Dragon TV TV series Heroes in Sui and Tang Dynasties.

• Portrayed by Zhang Fengyi in the 2014 Hunan Television TV series The Empress of China.

• Portrayed by Zheng Guo Lin in the 2014 TV series Heroes of Sui and Tang Dynasties 3 + 4.

• Portrayed by Winston Chao in the 2016 movie Xuanzang.

• Portrayed by Park Sung-woong in the 2018 Korean film The Great Battle.

• Portrayed by Geng Le in the 2021 Chinese TV series The Long Ballad 長歌行.

• Portrayed by Qin Junjie in the upcoming CCTV TV series ''Peace in Palace, Peace in Chang'An.

• Portrayed by Ma Yue in the TV series Ode to Daughter of Great Tang''.

References

• Emperor_Taizong_of_Tang (Wikipedia)

生平

早年經歷

隋文帝開皇十七年十二月戊午日（598年1月28日），李世民出生於岐州武功縣的慶善宮中（武功別館），是當時擔任隋朝岐州刺史的漢族官員李淵與竇氏所生的嫡次子。竇氏有四個兒子，一個女兒，按長幼順序為：李建成、平陽昭公主、李世民、李玄霸、李元吉。

隋煬帝大業九年（613年），母親在涿郡（治今北京市西南）病逝，鴻臚寺治禮郎高士廉看中了李世民，把外甥女長孫氏（登基後稱長孫皇后）許配給李世民為妻。

大業十一年（615年），雲定興被授以左屯衛大將軍，奉命援救在雁門關被突厥始畢可汗所率大軍圍困的隋煬帝。隋煬帝派人把詔書綁在木頭上，放進汾河讓詔書順流而下，希望有人看到詔書前來救援。雲定興向各地招募願意出征的軍士，李世民那年只有十六歲，前去應募從軍，被劃歸雲定興的帳下。雲定興手下只有兩萬新兵，且多是步兵。李世民向雲定興建議：突厥敢圍困天子，是認定我們沒有援軍。不如我們把軍隊前後拉開，延綿數十里，讓敵軍白天看見旌旗招展，晚上聽見鉦鼓聲聲，誤以為大軍壓境，如此才能不戰而勝。若他們知我虛實，兩兵相接，則勝敗難料。雲定興採納了李世民的疑兵之計攻突厥，突厥兵看到隋軍浩浩蕩蕩絡繹不絕，果然以為隋軍大批救兵到，於是解圍撤退。

隋大業十二年（616年），父親李淵升任隋朝右驍衛將軍。大業十三年（617年）正月，李淵又遷任太原郡留守，李世民也跟隨到太原，李建成、李元吉和他們的異母弟李智雲留在河東郡（今山西省永濟市）。李世民時年十八。魏刀兒來攻太原，李淵率兵攻打，不幸深入敵陣，無法衝出重圍。李世民以輕騎突圍而進，張弓射敵，所向皆披靡，救李淵於萬眾之中。其後敵步兵又至，李淵與李世民又奮擊，大破敵軍。

晉陽起兵

隋朝各地反聲四起，戰火瀰漫，民不聊生。李世民準備舉義兵，于是撫恤百姓，禮遇士兵，散財養客，江湖人士、俠客義士，莫不願效死力，為李唐起義兵做好充分準備。李世民在太原結納長孫順德、劉弘基、竇琮等人，與晉陽宮監裴寂和晉陽縣令劉文靜商議勸諫父親李淵起兵反隋。東突厥支持的定楊可汗劉武周占領了太原附近汾陽宮，隋煬帝不滿李淵和馬邑郡太守王仁恭無力阻止東突厥入侵。隋煬帝要將李淵和王仁恭捉拿帶到江都問罪，還沒有成行，又將其赦免。

當時，有李氏取代楊氏的讖語，隋煬帝因為擔心李渾的侄子李敏（煬帝的姐姐楊麗華的女婿）會應讖為帝，因此誅殺了李渾家族。李淵非常擔心，在李世民、裴寂的鼓動下，決心起兵反隋。偷偷召喚李建成、李元吉從河東，女婿柴紹從長安前來太原。七月，李淵誅殺了隋煬帝派來監視他的郡丞王威、武牙郎將高君雅，接著打著「勤王定亂，迎回隋天子」的旗號，正式開始於晉陽縣起兵，並且得到李氏宗族、姻親的響應，是為晉陽起兵。李淵以李世民為敦煌郡公、右領軍都督、統右三軍。

李淵派劉文靜出使東突厥得到了始畢可汗的支持，派李建成、李世民奪取西河郡。六月，正式起兵。李淵自為大將軍，以長子李建成、次子李世民為左右大都督，以四子李元吉留守太原，進兵大興城（長安）。

唐朝建立

七月，李世民隨李淵出征，李淵在山西霍邑與隋將宋老生二萬精兵相持於霍邑。恰值久雨糧盡，李淵與長史裴寂議論，不如暫且回太原，以後再圖謀舉事。李世民懇求李淵不要退卻。李世民說：「原本興立大義是為了拯救百姓，應當先攻入咸陽，號令天下；遇到小敵就回師，恐怕隨從起義之人將會一朝解體。回去守太原一城之地，這不過是賊寇所為罷了，怎麼能保全自己！」但是李淵不採納，催促命令引軍出發。李世民遂大哭於外，聲聞帳中。李淵召問其故，李世民說：「現在部隊憑藉正義而出動，前進、戰鬥就必定勝利，退回就一定會散夥。大家散夥於前，敵人趁機追擊於後，死亡將頃刻而至，因此悲傷。」李淵醒悟而停止撤兵。

八月，雨停，引師取霍邑。李世民怕宋老生不出戰，於是率領數名騎兵先到霍邑城下，拿著馬鞭指點比劃，好像圍城樣子，以激怒宋老生。宋老生果然發怒，開門出兵，背城列陣。李淵與李建成一起列陣於城東，李世民和柴紹列陣於城南。老生指揮兵士迅速前進，先逼近李淵，這時李建成忽然墜馬，宋老生趁機進攻，李淵與李建成部隊往後退卻。李世民自城南高地率領兩名騎兵急馳而下，衝斷了宋老生部隊，又領兵奮力進擊，敵軍大敗，各扔掉兵器逃跑。宋老生退回到城門，城上閘門放下，宋老生手拉繩子想上城，被砍死，於是霍邑平定。

到了河東，關中豪傑爭著奔赴參加義軍。李世民請求進軍入關，開永豐倉賑濟百姓，收服群雄及眾豪傑來謀取京都。李淵同意，從龍門渡黃河，先定渭北。關中有李世民的姐姐李三娘等人起兵響應。京都附近官民及豪傑紳士到軍門請求獻身報效義軍者日以千計，扶老攜幼，滿於麾下。李世民收納英俊，擇才而用，遠近聞者，皆來投靠。

唐軍在涇陽宿營，有優秀兵士九萬名，擊破反隋盜寇胡人劉鷂子，兼併其部下，留下殷開山、劉弘基屯駐長安舊城。李世民自己帶兵奔赴司竹，盜寇首領李仲文、何潘仁、向善志等都來相見，停留於阿城，獲得兵士十三萬人。長安父老送牛酒到營門勞軍者不可勝數，李世民都加以慰問，然後送走他們，東西一概不收。軍令嚴肅，秋毫無犯。接著與大軍一起平定京城。

十一月，李淵攻克大興，以代王楊侑為皇帝，尊隋煬帝楊廣為太上皇，李淵自為大丞相、唐王。攻克隋大興城後，李世民官拜京兆尹、受封秦國公。隴西的西秦霸王薛舉不滿李淵占據西京，派他的兒子薛仁杲來犯。李淵派李世民抵禦薛仁杲，李世民在扶風擊敗薛仁杲，薛舉暫時有投降李淵的念頭，被謀士郝瑗勸阻。義寧二年（618年）春，隋朝東都洛陽被瓦崗軍魏公李密圍攻，李淵派李建成和李世民率軍聲稱援助洛陽，想試探洛陽能否歸順自己。洛陽的官員拒絕了李淵的援助，李建成和李世民在此時不想與東都留守官員和李密爭奪洛陽的控制權，于是撤軍。三月初十（618年4月10日），李淵改封李世民為趙國公。三月，隋煬帝楊廣在江都被宇文化及所殺，五月，李淵廢黜楊侑，稱帝，改國號為唐，定都大興，易名長安，唐朝建立。李世民拜尚書令、晉為秦王。

統一中國

唐朝建立後，疆土只限于關中和河東一帶，尚未完全統治全國，因此，李世民經常出征，最終統一中國。自武德元年起，李世民親自參與四場大戰役。

• 其一，破薛舉，淺水原平定隴西薛仁杲（薛舉之子），平定祖宗之地。

• 其二，敗宋金剛、劉武周，收復並、汾失地，消滅北方地方軍閥。

• 其三，在虎牢之戰中，一舉殲滅中原兩大割據勢力—河南王世充和河北竇建德集團，消除河北、河南的地方勢力。

• 其四，重創竇建德餘部劉黑闥和山東的徐圓朗。

平定西秦

西秦薛舉自立為秦帝，再次攻打唐朝，兵鋒抵達涇州（今甘肅省涇川縣） ，唐高祖派李世民為西討元帥，抵禦薛舉。李世民深溝高壘，不肯與薛舉交戰，想要將薛舉拖垮。但此時李世民身患瘧疾，回後方修養。臨走前，李世民令代為指揮軍隊的劉文靜、殷開山不得擅自出兵。七月初九，劉文靜、殷開山因輕視而出擊薛舉，被敗于淺水原，唐軍大敗，傷亡十之五六。唐軍被迫撤回長安，劉文靜、殷開山被免職。薛舉獲勝後，聽從郝瑗的建議，準備進攻長安。八月初九，薛舉暴病而亡，其子薛仁杲繼位。八月十七，唐高祖再派李世民為元帥，抵禦薛仁杲。薛仁杲即位三個月後，唐軍出擊，在淺水原與薛仁杲的部將宗羅睺激戰。結果，唐軍擊潰了宗羅睺的軍隊，然後襲擊薛仁杲。薛仁杲被迫撤入高墌城，大批士兵降唐。薛仁杲只好降唐，李世民將他押送長安，被唐高祖處決。十二月初一，唐高祖任命李世民為太尉、使持節、陝東道大行台。

平定河東

武德二年（619年），劉武周對唐朝發動攻勢。九月十六攻陷太原，留守太原的李元吉棄城逃走，劉武周派宋金剛繼續向南進攻。唐高祖派宰相裴寂率軍抵禦，十月，裴寂大敗，今山西全境幾乎都落入了劉武周手中。唐高祖大驚，考慮放棄河東（山西省）。李世民請命親率大軍討伐劉武周。高祖同意，派他率領軍隊渡過黃河。李世民與宋金剛對峙，還是沒有馬上交戰，選擇相持將宋軍拖垮，同時派殷開山、秦叔寶率軍擊敗援助叛唐勢力的劉武周部將尉遲敬德、尋相。最終，武德三年（620年）四月，宋金剛糧草枯竭後退，李世民追擊，宋金剛大敗。尉遲敬德、尋相降唐，李世民持續追擊，劉武周、宋金剛逃往東突厥。山西全境都落入唐朝手中。

平定中原

武德三年（620年）夏，唐高祖再派李世民東征鄭國。619年，隋朝末代皇帝楊侗禪位給鄭王王世充，王世充稱皇帝，建立了鄭國。李世民兵至鄭都洛陽，王世充求和，李世民回絕，開始圍攻洛陽。同時，他派部下分別占領了鄭國周邊的城池。同年冬，除洛陽和王世充的侄子王弘烈守衛的襄陽之外，鄭國大部分地區都歸屬唐朝。王世充向河北的夏王竇建德求助。竇建德認為唐滅鄭國之後，就要兼併他的夏國，于是同意出兵。他派李大師勸李世民撤退，李世民扣留李大師，沒有回應竇建德。李世民在兵將中選派玄甲軍一千餘人，身著黑衣黑甲，自己率領秦叔寶、尉遲敬德、程知節、翟長孫作為指揮。

武德四年（621年）春，洛陽陷入絕境，夏軍尚未抵達，但唐軍也進入困局，洛陽城防依靠飛石弓弩使唐軍傷亡很大。唐高祖聽說竇建德已決定前來援助王世充，命李世民撤退。李世民派封德彞去長安稟明高祖，如果唐軍撤退，王世充勢力再振，以後很難取得現在的成功了。高祖于是同意李世民繼續圍攻洛陽。夏國前軍抵達，李世民派軍將其擊潰，然後致書竇建德，請他撤軍。竇建德的妻子曹皇后和大臣凌敬建議，應進攻山西南部的唐軍，竇建德沒有同意，繼續向洛陽進軍。李世民預料到竇建德的行動，留下李元吉指揮圍攻洛陽，自己則東進虎牢關結陣。兩軍在虎牢交戰，李世民打敗竇建德，將其俘虜。他將竇建德帶到洛陽，王世充見到大驚，想要放棄洛陽南逃襄陽，但他的部將表示現在唯一能依靠的就是竇建德，竇建德被擒，已經沒有勝算。王世充于是投降。逃回夏都洺州的曹皇后和齊善行隨後也投降唐朝。鄭國、夏國之地都歸屬唐朝。

自此李世民威望日隆，尤其是在虎牢之戰後班師返京時，受到長安軍民的隆重歡迎。高祖為賞賜李世民和李元吉鑄幣監各三爐，裴寂一爐，讓他們自己鑄幣。武德四年十月，封為天策上將，領司徒、陝東道大行臺尚書令，食邑增至二萬戶。李淵又下詔特許天策府自置官屬，李世民因此闢弘文館，收攬四方彥士入館備詢顧問，與秦王府相結合，儼然一個小內閣。

平定河北

竇建德被李世民被帶回長安後，被唐高祖處決。武德四年（621年）冬，夏將劉黑闥反抗唐朝，聲稱要為竇建德報仇。兗州徐圓朗名義上在王世充手下為魯王，在王世充失敗後歸順唐朝。這時，劉黑闥與徐圓朗結盟，一起反唐。劉黑闥接連擊敗高祖的堂弟淮安王李神通、義安王李孝常和曹國公李世勣。至此，他幾乎收複了原夏國疆域，定都洺州，自封為漢東王。武德五年（622年），高祖再派李世民和李元吉率軍討伐，經過一番戰鬥，三月廿六，李世民在洺水上築壩，然後將其摧毀，由此引發的洪水摧毀了漢東軍。劉黑闥逃到東突厥，而李世民則向東擊敗徐圓朗。高祖召李世民回朝，于是李元吉、李世勣、李神通、任瓌繼續進攻徐圓朗，四月初九，李世民返回長安。

玄武門之變與即位

618年，李淵建立唐朝為唐高祖，並立世子李建成為太子。太原起兵是李世民的謀略，高祖曾答應他事成之後立他為太子，但天下平定後，李世民功名日盛，而高祖猶豫不決。太子李建成隨即聯合四弟齊王李元吉，共同排擠李世民。同時，高祖的優柔寡斷，也使朝中政令相互衝突，加速了諸子的兵戎相見。太子、秦王和齊王的教書與皇帝的詔書具有同等效力，在命令相互衝突時，官員們只得執行最先到達的命令。

此後，長兄皇太子李建成知李世民終不肯屈為人臣，而李世民也認為是自己奠下唐朝開國的基業，遂與李建成、四弟齊王李元吉猜忌日深，兩派之間互相傾軋。李世民的手下人才濟濟，李建成的支持者只有李元吉和李淵的嬪妃尹德妃、張婕妤等人。

武德五年（622年）年底，劉黑闥得到東突厥頡利可汗的支持返回河北，在下博之戰大勝唐軍，李世民的堂弟淮陽王李道玄陣亡。劉黑闥再次恢復了原夏國的大部分領土。李建成的謀士王珪和魏徵建議太子要在戰爭中提升自己的聲望，李建成向父親請戰。高祖于是派李建成、李元吉率軍攻打劉黑闥。武德六年（623年），劉黑闥兵敗，被諸葛德威出賣，擒獲交給李建成。李建成在漢東故都洺州處決了劉黑闥，凱旋迴到長安。此時，唐朝基本統一中國。

接下來的幾年中，李世民兄弟之爭愈演愈烈。在此期間，東突厥入侵時，李建成、李世民都曾經率軍防禦。輔公祏在丹陽（今江蘇省南京市）反唐時，唐高祖任命李世民為江州道行軍元帥，攻打輔公祏，但很快取消了命令，而派李世民的堂兄趙郡王李孝恭代為出征。

武德七年（624年）六月，李建成暗中招募驍勇充當東宮衛士，郎將爾朱煥、校尉橋公山到仁智宮向避暑的唐高祖告發。唐高祖大怒，將李建成逮捕。李建成的親信慶州都督楊文幹恐懼，起兵謀反。高祖派李世民攻打楊文幹，許諾平定楊文幹後立他為太子。然而，李世民走後，李元吉和宰相封德彞、尹德妃、張婕妤等人都替李建成求情。李世民平定楊文幹歸來後，高祖並沒有廢黜李建成，而是指責李世民與李建成不和，將李建成的手下太子中允王珪、左衛率韋挺和李世民手下的天策兵曹參軍杜淹，全都流放到巂州（今四川涼山彞族自治州）。

唐高祖困于東突厥多次入侵，想要燒毀長安，遷都樊城。李建成、李元吉、裴寂都表示同意。而李世民堅持反對，所以計劃未能實施。同時，李世民也派親信張亮、王保等人前往洛陽，加強控制當地軍隊和結納山東豪傑。

李世民曾在李建成東宮飲酒，吐血數升，懷疑李建成下毒。唐高祖于是考慮派李世民出鎮洛陽，以防止兄弟之間的進一步衝突。但李建成、李元吉認為這會給李世民一個在洛陽培養勢力的機會，于是表示反對。高祖因此作罷。與此同時，李世民曾一度造訪李元吉府邸，李元吉想要刺殺李世民，李建成卻下不了決心，因而終止了行動。李建成有一匹烈馬，很容易摔倒騎手，他讓李世民試騎，導致李世民幾次摔倒，李世民向宇文士及表示對這種伎倆的不屑。

其中宰相裴寂、謀士王珪、魏徵、東宮衛士將領薛萬徹等追隨李建成、李元吉。秦府謀士杜如晦、房玄齡，將領秦叔寶、尉遲敬德、段志玄、侯君集、王君廓等跟從李世民。宰相陳叔達、渭北行軍典簽長孫無忌等暗中支援李世民。其餘將領李靖、李世勣，大臣宇文士及等保持中立。李世民手下房玄齡、杜如晦、長孫無忌一再勸說李世民先對李建成、李元吉下手，而魏徵則勸說李建成先攻打李世民。李建成勸唐高祖翦除房玄齡、杜如晦，以及李世民的親信尉遲敬德和程知節。留在李世民身邊的長孫無忌繼續勸說李世民先下手為強。

武德九年（626年）夏，東突厥侵犯唐邊境。高祖本來想要派李世民率軍抗擊，李建成向高祖建議由李元吉做統帥，率領李世民手下的大將尉遲敬德、程知節、段志玄、秦叔寶等人出征突厥。太子府率更丞王晊密報秦王：李建成想藉此控制秦王的兵馬，並準備在昆明池為李元吉餞行時，設伏兵殺李世民。于是李世民決定先發制人，讓尉遲敬德暗中召見房玄齡、杜如晦回府，夜間向高祖狀告李建成、李元吉淫亂後宮。高祖于是計劃第二天一早召見李建成、李元吉，召宰相裴寂、蕭瑀、陳叔達調查此案。次日，即武德九年六月初四庚申日（626年7月2日），李建成和李元吉通過首都長安城宮城的北門玄武門附近時，李世民帶領手下進行伏擊。他親自射出一箭，射殺了皇太子李建成，尉遲敬德殺死了齊王李元吉，史稱「玄武門之變」。

此後李世民的軍隊進宮，高祖得知情況後，知道大勢已去，讓出軍政大權予秦王，而建成、元吉則被宣布為作亂者，諸子則遭誅殺並從宗籍中除名。三天後（六月初七癸亥日，7月5日），李世民被立為皇太子，詔曰：「自今軍國庶事，無大小悉委太子處決，然後聞奏」。八月初九甲子日（9月4日），高祖退位稱太上皇，禪位於李世民。李世民登基，是為唐太宗。當年十月，追封李建成為息隱王，李元吉為海陵剌王。次年改元貞觀。642年，追複李建成為隱太子，李元吉為巢剌王，並將皇子李福過繼李建成為嗣（後來另一皇子李明也在唐高宗年間被出繼李元吉為嗣）。

貞觀之治

太宗在位期間，積極推行了府兵制、租庸調制和均田制，並加強科舉制等政策。貞觀二年（628年），當時的人口已因隋末戰爭而銳減，此時唐朝只有290萬戶，經太宗君臣23年的努力，社會安定、經濟恢復並穩定發展，至唐高宗永徽三年（652年），人口達到380萬戶，奠下了高宗、武則天、玄宗年間大唐盛世的基礎，史稱貞觀之治。

太宗本身也是個既英武又善辯之人，但是有鑑於帝位得之不易，加上隋煬帝本人亦以雄健爾雅善辯聞名，隋卻因此鑄下滅亡的大錯，因此在位期間，太宗鼓勵群臣批評他的決策和風格。其中魏徵廷諫了200多次，在廷上直陳唐太宗的過失，在早朝時多次發生了使太宗尷尬、下不了臺的狀況。晚年的太宗因國富民強，納諫的器度不如初期，偶爾也發生誤殺大臣的遺憾，但是大致上仍克制、保有納言的風範。

在民族政策方面，《資治通鑑》記載唐太宗在貞觀二十一年（647年）平定薛延陀時，曾對他的左右大臣說：「自古帝王皆貴中華，賤夷狄，朕獨愛之如一，故其種落皆視朕如父母。」，《貞觀政要》也記載了唐太宗在貞觀十三年（639年）封阿史那思摩為突厥可汗時說道：「中國百姓，實天下之根本，四夷之人，乃同枝葉，擾其根本以厚枝葉，而求久安，未之有也。初不納魏徵言，遂覺勞費日甚，幾失久安之道。」

太宗即帝位不久，按秦王府文學館模式，新設弘文館，進一步儲備天下文才。另外，太宗精擅書法，以行書寫碑，稱「飛白」，聞名後世。著名作品有《溫泉銘》、《晉祠銘》等。晚年太宗著《帝範》一書以教戒太子李治，總結了他的施政經驗，同時自評一生功過。史家曾疑太宗生前，指定以東晉書法大家王羲之所作《蘭亭集序》為陪葬品。近年據考古學家和歷史學者研究，《蘭亭集序》應該不在太宗之昭陵，而在高宗、武則天所合葬的乾陵之中。

唐太宗與身邊大臣魏徵、王珪、房玄齡、杜如晦、虞世南、褚遂良等的對答也在開元十八（730年）、十九年間被吳兢輯為《貞觀政要》一書，以發揚太宗勵精圖治的治國精神。

貞觀初政

太宗即位十天，就將大批宮女簡放出宮，送她們回家，這樣她們在民間成家。太宗冊封其妻長孫氏為皇后，長子李承乾為皇太子。

太宗定勛臣爵邑，第一等為長孫無忌、房玄齡、杜如晦、尉遲敬德、侯君集。皇帝的堂叔淮安王李神通不滿自己位次在房杜之下時，太宗說房杜運籌帷幄，功勞大于在河北全軍覆沒的李神通。這讓其他反對之聲平息，因為他們見到太宗至公行賞，不私其親，將李神通這樣的宗室排在低位。太宗還以王爵之禮安葬了李建成和李元吉，並讓他們的原來的屬官參加了葬禮。

太宗從被立為太子之後就開始調整朝廷人事，任命自己信任的房玄齡等人成為宰相。而蕭瑀、陳叔達因為在皇帝面前爭忿，而雙雙被罷免。蕭瑀很快就重新入相，他在太宗朝屢遭罷黜和複職。太宗非常重視官員對朝政的批評，使他認為朝廷的弊政得以改變。太宗特別信任魏徵，接受了魏徵的很多建議。黃門侍郎王珪有密奏，交給侍中高士廉上達，高士廉沒有奏報太宗。太宗于是將高士廉出為安州大都督。太宗以隋煬帝為鑑，賞賜願意進諫的官員，尤其是魏徵和王珪。太宗對思想持開放態度，其中在文化上，試圖努力調和道教與佛教的矛盾，這體現在他晚年所作的《大唐三藏聖教序》中。

燕郡王李藝本是隋末幽州軍閥，後歸順唐朝，他在武德年間與李建成親近，且得罪過李世民。太宗即位後，李藝不自安。貞觀元年（627年）正月，他在豳州叛亂。但很快被平定，李藝逃亡中被殺。四月，高祖的堂弟、涼州（今甘肅省武威市）都督長樂王李幼良的手下無賴子弟侵暴百姓，並且私下與羌胡貿易。太宗派宇文士及前去調查，李幼良的部下驚恐萬分，密謀挾持他逃亡突厥。太宗得知此事後，賜李幼良自盡。九月，幽州（今北京市）都督王君廓入朝時，懷疑長史李玄道告發他的不法之事，于是殺驛吏逃亡突厥，途中被鄉民所殺。十月，嶺南酋長馮盎、談殿等互相攻擊，有人報告馮盎謀反，太宗在魏徵的建議下，派使者安撫馮盎，馮盎遣子入朝。

當年二月，太宗見天下州縣過多，將許多州縣加以合併。並在州縣以上設置「道」，將唐朝分為十道：關內道、河南道、河東道、河北道、山南道、隴右道、淮南道、江南道、劍南道、嶺南道。

滅東突厥

武德九年（626年）八月，因唐朝發生玄武門之變，政局不穩，東突厥伺機入侵，攻至距首都長安僅40裡的涇陽（今陝西咸陽涇陽縣），京師震動。此時，長安兵力不過數萬，剛剛即位的太宗被迫設疑兵之計，親率高士廉、房玄齡等6騎在渭水隔河與頡利可汗對話，怒斥頡利、突利二可汗背約。太宗贈予頡利可汗金帛財物，以求突厥退軍，並與之結「渭水之盟」，突厥兵於是退去。《唐語林》記載唐太宗「空府庫」以求突厥退軍，在突厥歸途時派李靖伏擊，奪回了財物，以及數萬匹馬。之後，太宗勵精圖治，並且挑撥頡利、突利二可汗和突厥與鐵勒諸部的關係。627年，東突厥內部出現分裂。反對頡利可汗的薛延陀、回紇、拔也古、同羅諸部落對其變革國俗和推行的政令不滿，另立薛延陀為可汗。突利可汗也暗中與唐聯絡，並與頡利可汗決裂。臣服于東突厥的契丹首領大賀摩會也歸順唐朝，太宗冊封薛延陀可汗夷男為真珠可汗。同時東突厥又遇到大雪氣候，牲畜大多被凍死餓死，突厥勢力漸弱。

突厥這時沒有力量庇護最後一個隋末割據者——夏州割據勢力首領梁師都，柴紹和薛萬均率軍圍攻梁都朔方（今陝西省榆林市），貞觀二年四月二十六壬寅日（628年6月3日），朔方人梁洛仁殺梁師都，歸降唐朝，唐朝統一全國。

太宗決心挑戰東突厥在東亞的霸主地位，於629年八月任命李靖、李世勣、柴紹、李道宗等為行軍總管，令其出師塞北。各路大軍由李靖總制，蘇定方為先鋒，出兵征討東突厥。唐軍在李靖的調遣下，貞觀四年（630年）三月頡利兵敗被俘，而後被押送到長安，東突厥滅亡。

天可汗

東突厥滅亡後，溫彥博主張將突厥人留在唐朝邊防體系之內作為防禦緩衝，魏徵則主張將突厥人驅逐塞外。太宗接受了溫彥博的建議，于是唐朝在東突厥突利可汗故地設置順、祐、化、長四州都督府，頡利可汗故地置定襄都督府、雲中都督府，仍由部落酋長作為都督、刺史，而沒有任命新的封疆大吏來統治。漠北和西域諸國君主在長安尊稱太宗為「天可汗」，意為天下總皇帝或天下共主。「天可汗」除了是一種對唐朝皇帝的榮銜，還是一種有實質意義的國際組織體系，以維持當時絲綢之路途徑各同盟國的集體安全與貿易秩序。

貞觀五年（631年），太宗命大臣討論郡縣制和封建制的利弊，魏徵、李百藥等人反對封建制，顏師古建議讓宗室子弟和功臣擔任刺史，勿令過大，間以州縣，雜錯而居，各取郡縣制和封建制的優勢。太宗同意了顏師古之議。東突厥滅亡後，大臣多次請求太宗在泰山封禪，太宗開始表示拒絕，後來他的信念動搖時，又被魏徵一再勸阻，魏徵指出封禪會導致百姓供頓勞費、開支巨大，而且讓遠夷君長看到中原因戰亂導致的荒蕪，對國防也不益。太宗于是採納了他的建議。

貞觀八年（634年），太宗派李靖、蕭瑀等十三位高官為諸道黜陟大使，巡視地方官能否查明民苦，安撫貧民，選拔賢能。李靖最初推薦魏徵，太宗不同意，說魏徵要留在自己身邊指出他的錯誤，他一天都不能讓魏徵離開。

平定吐谷渾

吐谷渾可汗伏允聽信大臣天柱王的建議，屢次侵犯唐朝的西部邊境。伏允曾想讓他的兒子尊王迎娶唐朝公主，太宗堅持讓尊王來長安舉行婚禮，于是和親未成。634年，扣留唐朝使者趙德楷，六月，太宗以段志玄、樊興為行軍總管，討伐伏允。吐谷渾軍隊機動性強，避免正面交鋒，段志玄雖未戰敗，但也未能大獲全勝。十二月，又以李靖、侯君集、李道宗、李大亮、李道彥、高甑生等為行軍總管，率領薛萬均、薛萬徹、契苾何力等將領，大舉討吐谷渾。635年，李靖大軍隊擊潰吐谷渾，伏允敗走，被部下所殺。伏允之子慕容順殺死天柱王，自立為可汗，投降唐朝，太宗冊封慕容順為吐谷渾可汗。慕容順死後，636年，太宗冊封慕容順之子諾曷缽為吐谷渾可汗。

氏族志

635年五月，太上皇高祖李淵駕崩，太宗在服喪期間，曾短暫讓太子李承乾監國，六月，太宗重新聽政，此後仍授權李承乾處理細務。636年春，太宗任命皇弟、皇子為刺史，按授命之地更改王號。636年秋，長孫皇后去世，太宗悲痛哀悼，親筆為她題碑文。

637年夏，太宗重新考慮分封制，制定了刺史襲封制度。將皇弟、皇子和功臣除保留現有職位外，還獲得了州刺史的職位，並可以傳給他們的後代。于是設立了35個世襲刺史及都督。不久後，這個計劃遭到了以長孫無忌為首的功臣們的反對，639年，太宗于是取消了這一制度。

太宗不滿崔、盧、李、鄭等山東士族，認為他們自衿高門。638年，命高士廉、韋挺、令狐德棻、岑文本編撰《氏族志》，意圖將士族根據名望、功勳、善惡分為九類。然而，在高士廉提交的初稿中，仍然將崔民幹的博陵崔氏列為第一等。太宗不滿，因為他指出高士廉只看傳統名望，不看近世功勳。因此，太宗親自幹預修改，以皇族李姓為首，外戚長孫氏為次，將崔氏家族降為三等。

和親吐蕃

在青藏高原上，吐蕃日漸興起，至六世紀末與吐谷渾、蘇毗為高原上三大勢力。七世紀初，贊普松贊幹布即位，統一了高原，又征服了位於西藏西部的蘇毗、阿里地區的羊同和尼婆羅（今尼泊爾）。

634年，吐蕃贊普松贊幹布遣使與唐朝修好，唐朝也派使臣馮德遐入蕃。636年，松贊幹布派專使去長安請婚，唐朝不允。638年，松贊幹布遂藉口唐朝屬國吐谷渾從中作梗，親自指揮大約20萬吐蕃軍，出兵入侵吐谷渾，並開始攻擊唐朝的松州（今四川阿壩藏族羌族自治州）。但同時松贊幹布又派遣使者到唐朝國都長安再次請求，並宣稱他們打算歡迎公主。唐太宗派侯君集為當彌道行軍大總管指揮5萬軍隊，執失思力、牛進達、劉簡協助，援救松州。與此同時，吐蕃軍正在圍困松州的首縣－嘉誠（今四川松潘），但唐軍先遣部隊在牛進達指揮下，打敗了吐蕃軍。唐軍在松州大勝吐蕃軍，但唐朝也見識到了吐蕃的力量。640年，松贊幹布又派大臣祿東贊使唐求婚，唐太宗便以宗室之女文成公主許嫁於吐蕃贊普松贊幹布，並派禮部尚書江夏王李道宗持節護送。641年，唐室文成公主下嫁於吐蕃的松贊幹布，吐蕃贊普于是接受唐朝的冊封。《新唐書》記載文成公主入蕃時，松贊幹布親迎於柏海。吐蕃派豪族子弟到長安學習《詩》、《書》。唐高宗繼位後，又通過賞賜松贊幹布和文成公主把各種漢地的生產技術轉入吐蕃。

觀史書己

貞觀九年十月，即李淵死後五個月，李世民第一次要求觀覽《起居注》，未遂。

《貞觀政要·卷七·論文史第二十八》記載：貞觀十三年，褚遂良為諫議大夫，兼知太宗《起居註》。唐太宗欲查看起居註，褚遂良以「不聞帝王躬自觀史」為由拒絕了。唐太宗說：「朕有不善，卿必記耶？」褚遂良說：「臣職當載筆，何不書之？」黃門侍郎劉洎進言：「人君有過失，如日月之蝕，人皆見之。設令遂良不記，天下之人皆記之矣。」《舊唐書·褚遂良傳》和《資治通鑑·唐紀十二》也載有此事。

次年（640年），唐太宗再度要求看《起居注》，宰相房玄齡等人就刪減整理國史，撰寫成《高祖實錄》和《太宗實錄》各二十卷。當太宗見到「六月四日事，語多微文」——指史官對當年玄武門事變內容含糊其辭，多有隱諱文飾之語，便以當年房玄齡勸他政變時「遵周公之事，外寧區夏，內安宗社」的說法，向房玄齡表示：不必替他遮遮掩掩，反正玄武門事件本來就是像「周公誅管、蔡，季友鴆叔牙」之義舉，目的是為了「安社稷、利萬民」，要求「削去浮詞，直書其事」。《資治通鑑·唐紀十三》亦有記載。

這一行為遭到章太炎指責：「太宗即立，懼於身後名，始以宰相監修國史，故兩朝《實錄》無信辭。」呂思勉、黃永年等學者也附和章太炎的觀點，認為唐太宗對史書記載有所修飾。

諸子奪嫡

皇子親王出任地方刺史，唯有魏王李泰、晉王李治留在長安。李泰受到太宗的重視。太宗因為李泰喜歡文學，允許李泰聘請文人作為僚屬，編纂《括地誌》。長孫皇后去世後，因為李泰受寵，出現了太宗可能讓他取代太子李承乾的議論，李承乾的支持度開始減弱。

到642年，李泰已經有了取代太子的野心，一些官員開始分化為太子派和魏王派。太宗在魏徵、褚遂良的勸說下，採取行動表明穩固太子的地位。但他繼續偏愛李泰的做法，不斷引起大臣們的猜測。643年春，魏徵去世，太宗悲痛哀悼，親自為魏徵立碑，並在魏徵去世前，許諾將女兒衡山公主嫁給魏徵的兒子魏叔玉。太宗派人在凌煙閣繪製二十四功臣圖。

643年春，太宗五子齊王李祐因長史權萬紀常加于他諸多限制，而憤憤不平，于是他殺了權萬紀，在齊州起兵叛亂。太宗派李世勣討伐打李祐，大軍未至，李祐就被自己的部下杜行敏俘送到長安，太宗命他在內侍省自殺，同黨四十四人被誅，其餘不問。

太子李承乾經常說突厥語，穿著突厥服裝，甚至在自己的住所里搭起帳篷，模仿突厥可汗。李承乾怕太宗廢黜自己而立李泰，與侯君集、太宗之弟漢王李元昌、將軍李安儼、他的姑表兄趙節、杜如晦之子杜荷等人合謀奪位。在追查李祐之亂時，李承乾的侍衛紇幹承基被牽連，為了自救，他揭發李承乾的陰謀。太宗聞訊大驚，命長孫無忌、房玄齡、蕭瑀、李世勣，會同大理、中書、門下等官署進行聯合調查。太宗在通事舍人來濟的建議下，太宗廢黜李承乾的太子之位，而沒有殺他，命李元昌自殺，侯君集、李安儼、趙節、杜荷被處決。

李承乾被廢黜後，太宗向李泰許諾，立他為太子。但隨著深入調查，太宗認為李承乾的謀反是受到李泰的逼迫，因此決定廢黜李泰。

《資治通鑑》記載，太宗貞觀十七年廢太子李承乾之後、改立李治為皇太子之前，李世民之三子一弟（長子李承乾、四子李泰、五子李祐、及七弟李元昌）俱謀取帝位，致太宗心灰意冷之曲折，史載：「承乾既廢，上御兩儀殿，群臣俱出，獨留長孫無忌、房玄齡、李世勣、褚遂良，謂曰：『我三子一弟，所為如是，我心誠無聊賴！』因自投於床，無忌等登前扶抱，上又抽佩刀欲自刎，遂良奪刀以授晉王治。」

太宗決定立晉王李治為太子，李承乾流放了黔州，李泰出居均州。太宗為太子李治選良家女充實東宮，被李治推辭。太宗懷疑李治的仁弱性格，是否足以繼承天下，他諮詢長孫無忌是否可以立自己和隋煬帝之女楊妃之子吳王李恪為太子，被長孫無忌堅決反對而未成。

由于魏徵生前曾推薦侯君集和杜正倫有宰相之才，太宗開始懷疑魏徵也參與了陰謀。于是撲倒了自己撰寫的魏徵之碑，取消了魏叔玉與衡山公主的婚約。

征討高句麗

642年冬，高句麗發生政變，最終導致了唐朝和高句麗的戰爭。642年天，高句麗榮留王不滿東部大人淵蓋蘇文專橫，與他的大臣密謀殺死淵蓋蘇文。淵蓋蘇文得到消息，發動政變，殺死了榮留王和同謀官員。擁立榮留王的侄子高藏為王，並自封為「大莫離支」攝政。有人建議攻打高句麗，最初太宗表示拒絕。

644年，高句麗攻打新羅，新羅請求唐朝援助。為征討淵蓋蘇文和保護唐朝的盟友新羅，唐太宗認為有必要對高句麗開戰。他逮捕了蓋蘇文派到唐朝的使者，宣布其弒逆之罪。644年，太宗率領李世勣、李道宗、張亮和長孫無忌統軍10萬親征高句麗。645年，太宗率領唐軍攻占了遼東（今遼寧省遼陽市），衝破高句麗的防線準備攻打高句麗國都平壤，似乎大功在即。太宗親自率領唐軍三萬，擊敗高句麗將軍高延壽、高惠真率領的十五萬大軍，圍攻安市城（今遼寧省鞍山海城市）。不料在安市受阻，再也無法前行。深秋時節，唐軍糧草枯竭，冬天將至，太宗于是撤軍。他後悔貿然親征，說：「魏徵若在，不使我有是行也。」他重新為魏徵立碑，召見魏徵妻兒，深加勞賜。

在這之後，太宗對高句麗的進攻僅維持在一些小規模的突襲。646年，唐朝與回紇擊滅薛延陀後，647年，唐太宗令牛進達率兵從海上、李世勣率兵從陸路攻打遼東半島。648年，太宗再派薛萬徹率軍從海上攻打鴨綠江口。隨後，唐開始集結陸海部隊準備在649年再一次大規模攻高句麗。不過太宗於649年去世後，新皇帝唐高宗暫停東征的計劃。668年，高宗聯合新羅滅亡高句麗，載籍戶數69.7萬。並建立安東都護府等加以控制遼東。

滅薛延陀

東突厥滅亡後，薛延陀的真珠可汗乙失夷男接管了東突厥的故土。薛延陀表面臣服於唐朝，暗中卻擴充自己的力量。638年，對于薛延陀逐漸強大，太宗怕之後難以控制，于是給真珠可汗的兩個兒子拔灼、頡利苾授予小可汗的頭銜，試圖在他們內部製造矛盾。

639年夏，突利可汗之弟結社率與突利可汗之子賀邏鶻勾結，計劃刺殺太宗。他們本打算等著晉王李治一早離開行宮時，趁機襲擊。而到了計劃的當天，晉王沒有離開宮殿，結社率于是提早行動，但很快失敗，被俘虜處決。這次事件之後，大臣們建議將突厥人從河套地區的黃河以南遣返到黃河以北。太宗也試圖恢復東突厥，以抗衡薛延陀的崛起。639年秋，太宗冊封突厥王族懷化郡王李思摩（阿史那思摩）為乙彌泥孰俟利苾可汗，作為重建的東突厥國家的首領，將諸州安置的所有突厥和胡人都交給了他。突厥人害怕薛延陀，不敢出塞。太宗下詔讓真珠可汗與李思摩保持和平，各守漠北和漠南，不互相攻擊。在真珠可汗保証不進攻後，突厥人于是出塞在漠南建牙。

薛延陀為避免新恢復的東突厥站穩腳跟，與其進行了多次戰爭。641年冬，真珠可汗聽說太宗即將在泰山封禪，無法支持東突厥，于是派其子大度設率軍攻打東突厥。李思摩被迫退入長城。太宗為保住東突厥，命李世勣與張儉、李大亮、張士貴、李襲譽率軍攻打薛延陀。李世勣很快在諾真河（流經今內蒙古包頭市）擊敗大度設，大度設逃走。

642年，薛延陀儘管名義上順從唐朝，但已經構成了嚴重的威脅。太宗這時有兩種選擇：武力征服或將女兒嫁給真珠可汗進行和親。唐朝將領、契苾部落的首領契苾何力，被部下擄走，獻給薛延陀。為了贖回契苾何力，太宗同意將女兒新興公主嫁給真珠可汗，真珠可汗于是釋放了契苾何力。643年，唐太宗認為自己向真珠可汗許諾和親並不明智，所以向薛延陀要聘禮：五萬匹馬、一萬頭牛和駱駝、十萬隻羊。真珠可汗同意，但無法立即交納。太宗以此為由，取消了婚約。

但是644年，趁太宗征伐高句麗的機會，薛延陀部隊發起新一輪攻勢，擊敗東突厥，東突厥部眾拋棄了可汗李思摩，逃回唐朝境內。阿史那思摩只得逃回雲州，太宗以他為右武衛將軍。隨後，高句麗尋求薛延陀援助，但夷男希望避免與唐朝直接戰鬥。

645年，夷男死後，他的兒子多彌可汗拔灼開始和唐軍作戰，攻打唐朝黃河以南和夏州。646年，唐將喬師望、執失思力率軍反擊並打敗拔灼後，薛延陀的附庸回紇、僕骨、同羅等鐵勒部落也乘機出兵造反。太宗得知後，派李道宗、阿史那社爾、執失思力、契苾何力、薛萬徹、張儉率軍大舉進攻薛延陀。薛延陀受到多方攻擊，回紇軍將多彌可汗殺死。餘下的薛延陀人紛紛逃亡，擁立拔灼的堂兄咄摩支為伊特勿失可汗，咄摩支向唐朝表示取消可汗之號。李世勣軍至鬱督軍山，咄摩支的部落還想頑抗，被唐軍擊敗。咄摩支向唐軍投降，被帶到長安，結束了其對漠北的統治。薛延陀滅亡後，其他臣服于薛延陀的部族，此時也都表示臣服于唐朝，以太宗為天可汗。

太宗於鐵勒故地設六府七州：瀚海府（回紇）、金微府（僕骨）、燕然府（多濫葛）、盧山府（思結）、龜林府（同羅）、幽陵府（拔野古）。七州：皋蘭州（渾）、高闕州（斛薛）、雞鹿州（奚結）、雞田州（阿跌）、榆溪州（契苾）、蹛林州（思結別部）、窴顏州（白霫）。由燕然都護府管理，治所在陰山之麓（今內蒙古杭錦後旗），轄境東到大興安嶺、西到阿爾泰山、南到戈壁、北到貝加爾湖的整個蒙古高原。回紇的首領吐迷度，雖順服唐朝，但也試圖控制漠北，648年他被侄子謀殺，直到九十多年後，回紇汗國才得以建立。

設立安西四鎮

唐太宗滅東突厥後，開始對西域（即現代新疆和中亞地區）的西突厥以及一些鬆散結盟綠洲國家的施加軍事實力，其主要針對西突厥，以恢復兩漢以來對西域的統治。從640年開始，太宗進行一系列針對西突厥及其在塔里木盆地綠洲僕從國的戰役。西突厥與唐朝之間的鬥爭，持續到太宗之子高宗在位時的657年，西突厥戰敗被唐朝徹底征服。

632年，疏勒國、于闐國向唐朝入貢，635年，處月國（伊犁河流域）向唐朝入貢，636年，朱俱波（今新疆葉城）向唐朝入貢。高昌王麴文泰原本臣服于唐朝，因為攻打焉耆，就和唐朝的矛盾越來越大，他與西突厥欲谷設聯合，阻礙西域商路，進攻唐朝的伊州。639年冬，太宗以侯君集為交河道行軍大總管，與薛萬均率兵出擊高昌王麴文泰。640年，唐軍至磧口，麴文泰驚懼而病死。其子麴智盛即位後不久，侯君集圍城，麴智盛請罪，侯君集要求他出城投降，麴智盛沒有同意。侯君集擊敗西突厥在可汗浮圖城的援軍，麴智盛于是獻城投降唐軍。高昌國三州、五縣、二十二城，八千戶、三萬餘人歸屬唐朝，高昌國結束。魏徵指出在高昌駐軍，花費和人力成本都很高，建議太宗讓麴智盛繼續為高昌王。太宗沒有同意，唐朝在高昌設置西州，將其全境併入唐朝的版圖。

640年，唐朝在交河城設安西都護府，用以針對西突厥和管理西域。焉耆王龍突騎支協助唐朝征討高昌，之後又與西突厥結盟，644年，西突厥的盟友焉耆攻打西州，安西都護郭孝恪為西州道行軍總管，從安西（即高昌）出兵討伐依附西突厥的焉耆，佔領焉耆，俘虜國王龍突騎支，立其弟龍慄婆准攝國事。但後來，西突厥大臣屈利啜隨後攻陷焉耆，俘獲龍慄婆准，焉耆再次脫離唐朝。屈利啜懼怕唐朝勢力，不久撤出，焉耆貴族立龍突騎支堂弟龍薛婆阿那支為王。

648年，唐太宗派遣阿史那社爾、郭孝恪率軍討伐依附西突厥的焉耆和龜茲（今新疆阿克蘇地區庫車縣），唐軍擊斬龍薛婆阿那支，立他的堂弟龍先那准為王。阿史那社爾進軍龜茲，俘虜其王白訶黎布失畢，立其弟為王，征服兩國。然後疏勒和于闐歸附唐朝，將安西都護府遷至龜茲，撫寧西域，統龜茲、焉耆、于闐、疏勒四國，史稱安西四鎮。

貞觀疆域

在北方，貞觀四年（630年），唐軍滅亡東突厥，漠南成為唐勢力範圍。貞觀二十年（646年），又一舉消滅了薛延陀汗國，至此大漠南北廣大地區皆為唐的勢力範圍。唐朝廷在漠北設立安北都護府，在漠南設立單于都護府，建立了南至羅伏州（今越南河靜）、北括玄闕州（後改名余吾州，今安加拉河地區）、西及安息州（今烏茲別克斯坦布哈拉）、東臨哥勿州（今吉林通化）的遼闊疆域。

在西北，貞觀四年，唐朝廷在伊吾七城設立西伊州，開始經營西域。貞觀二十二年（648年），郭孝恪擊敗龜茲國，把安西都護府治所遷至龜茲。

在東北，645年唐太宗征討高句麗未果，唐高宗在668年乃聯合新羅滅高句麗，設立安東都護府。

漸不克終

面對自己空前的文治武功，太宗到晚年也出現一些過失。首先納諫不如貞觀早期積極，比如貞觀十年，魏徵發現他「漸惡直言」。其次奢侈之風日重。不過晚年他還是能反省自己過度奢靡的錯誤。司馬光說唐太宗：「好尚功名，不及禮樂，父子兄弟之間，慚德多矣」。同時，太宗晚年也由早年的清靜轉為奢縱，營建宮殿，計劃封禪泰山等，並自辯「百姓無事則驕逸，勞役則易使」，魏徵因此諫到「恐非興邦之至言，豈安人之長算？」不過由于太宗晚年能夠清醒認識自己的問題，所以也能進行調整，因此雖然太宗晚年存在這些過失，最終沒有出現敗亡的危機，「功大過微，故業不墮」，維持了貞觀之治的局面。

與拜占庭帝國的聯繫

《舊唐書》和《新唐書》提到了拂菻（拜占庭帝國）幾次出使唐朝。認為拂菻相當于之前的大秦（漢代時指羅馬帝國）。643年波多力（君士坦斯二世）向太宗皇帝派遣使臣，獻上紅玻璃和綠寶石等禮物。這些史書也粗略記載了拂菻的風俗和君士坦丁堡的城牆，以及大食（阿拉伯帝國）大將軍摩栧（穆阿維葉一世，在成為哈里發之前擔任敘利亞總督）將其包圍，迫使拜占庭人請和的戰爭。薩珊帝國的最後一位統治者伊嗣俟三世在哈里發政權攻打波斯核心臟地帶時，派遣使者到中亞費爾幹納的宗主國唐朝尋求太宗皇帝的援助。這可能促使拜占庭人在敘利亞被穆斯林占領的情況下，派遣使節前往中國。唐朝的史料還記錄了在伊斯蘭哈里發征服波斯後，薩珊王朝的王子卑路斯三世逃往唐朝的情況。

在太宗統治下中國向中亞擴張，似乎已經引起了西方世界的注意。狄奧菲拉克特·西莫卡塔是希拉克略統治時期的拜占庭帝國歷史學家，他寫道，桃花石（Taugast、Taugas、古突厥語: Tabghach，一說語源來自建立北魏的鮮卑族拓跋氏），是一個偉大的東方帝國，統治著突厥民族, 首都在印度東北約1500英里處，稱之為胡姆丹（來自突厥語Khumdan，意思是長安）。那裡有偶像崇拜，但人們很聰明，遵照正義公正的法律而生活。他將中國描繪為被一條大河（即長江）分割，這條大河是兩個交戰敵對國家之間的邊界。在拜占庭皇帝莫里斯統治期間，北方人黑衣國征服了南方的紅衣國。該記述可能與隋文帝滅亡陳朝、統一中國有關。西莫卡塔將桃花石的統治者稱為ταϊσαν，解釋為天之子，可能是天子之意，也可以與當時統治者太宗一詞的對音有關。

去世

貞觀二十二年（648年）正月，唐太宗撰寫《帝範》十二篇頒賜給太子李治。貞觀二十三年（649年），唐太宗得了痢疾（一種傳染病），醫治最終無效（一說是服用天竺長生藥致暴病不救），命李治到金掖門代理國事。貞觀二十三年五月二十六日（649年7月10日），唐太宗李世民崩逝于終南山翠微宮含風殿內，享年五十一歲，在位二十三年，初謚文皇帝，廟號太宗，葬唐昭陵（位于今中國陝西省禮泉縣東北50多里山峰上），唐高宗上元元年（674年）加謚文武聖皇帝，唐玄宗天寶八年（749年）加謚文武大聖皇帝，天寶十三年（754年）加謚文武大聖大廣孝皇帝。

評價

• 《貞觀政要》贊貞觀之治：官吏多自清謹，王公妃主之家，大姓豪猾之伍，無敢侵欺細人。商旅野次，無複盜賊，囹圄常空，去年犯死者僅二十九人。又頻致豐稔，米斗三錢，馬牛布野，外戶不閉，行旅自京師至于嶺表，自山東至于滄海，皆不齎糧，取給于路。入山東村落，行客經過者，必厚加供待，或發時有贈遺。此皆古昔未有也。

• 後晉官修正史《舊唐書》劉昫等的評價是：「史臣曰：臣觀文皇帝發跡多奇，聰明神武。拔人物則不私于黨，負志業則咸盡其才。所以屈突、尉遲，由仇敵而願傾心膂；馬周、劉洎，自疏遠而卒委鈞衡。終平泰階，諒由斯道。嘗試論之：礎潤雲興，蟲鳴螽躍。雖堯、舜之聖，不能用檮杌、窮奇而治平；伊、呂之賢，不能為夏桀、殷辛而昌盛。君臣之際，遭遇斯難，以至抉目剖心，蟲流筋擢，良由遭值之異也。以房、魏之智，不逾于丘、軻，遂能尊主庇民者，遭時也。或曰：以太宗之賢，失愛于昆弟，失教于諸子，何也？曰：然，舜不能仁四罪，堯不能訓丹朱，斯前志也。當神堯任讒之年，建成忌功之日，苟除畏逼，孰顧分崩，變故之興，間不容髮，方懼「毀巢」之禍，寧虞「尺布」之謠？承乾之愚，聖父不能移也。若文皇自定儲于哲嗣，不騁志于高麗；用人如貞觀之初，納諫比魏徵之日。況周發、周成之世襲，我有遺妍；較漢文、漢武之恢弘，彼多慚德。跡其聽斷不惑，從善如流，千載可稱，一人而已！贊曰：昌、發啟國，一門三聖。文定高位，友于不令。管、蔡既誅，成、康道正。貞觀之風，到今歌詠。」

• 北宋官修正史《新唐書》歐陽修、宋祁等的評價是：「甚矣，至治之君不世出也！禹有天下，傳十有六王，而少康有中興之業。湯有天下，傳二十八王，而其甚盛者，號稱三宗。武王有天下，傳三十六王，而成、康之治與宣之功，其餘無所稱焉。雖《詩》、《書》所載，時有闕略，然三代千有七百餘年，傳七十餘君，其卓然著見于後世者，此六七君而已。嗚呼，可謂難得也！唐有天下，傳世二十，其可稱者三君，玄宗、憲宗皆不克其終，盛哉，太宗之烈也！其除隋之亂，比跡湯、武；致治之美，庶幾成、康。自古功德兼隆，由漢以來未之有也。至其牽于多愛，複立浮圖，好大喜功，勤兵于遠，此中材庸主之所常為。然《春秋》之法，常責備于賢者，是以後世君子之欲成人之美者，莫不嘆息于斯焉。」

• 《新唐書·北狄列傳》：唐之德大矣！際天所覆，悉臣而屬之；薄海內外，無不州縣，遂尊天子曰「天可汗」。三王以來，未有以過之。至荒區君長，待唐璽纛乃能國；一為不賓，隨輒夷縛。故蠻琛夷寶，踵相逮於廷。

• 陸九淵《象山語要·卷三十一·論德仁功利》：「太宗富有天下，貴為天子，功業皆其所自致，而能俯首抑意，聽拂逆之辭于疇昔所惡之臣。嗚呼！此其所以致貞觀之治，庶幾于三代之王者乎？」

• 朱熹與陳亮書：「太宗之心，則吾恐其無一不出于人慾也。直以其能假仁假義，以行其私。而當時與之爭者，才能知術既出其下，又不知有仁義之可飭。是以彼善于此，而得以成其功爾。」「論後世人，不當盡繩以古人禮法。畢竟高祖不當立建成。」「太宗功高，天下所系屬，亦自無安頓處，只高祖不善處置了。」

• 文天祥《古代狀元卷:文天祥殿試卷》：太宗全不知道、閨門之恥、將相之誇、末年遼東一行、終不能以克其血氣之暴、其心也驕。

• 元朝戈直在《貞觀政要》集論中說：「夫太宗之於正心修身之道，齊家明倫之方，誠有愧於二帝三王之事矣。然其屈己而納諫，任賢而使能，恭儉而節用，寬厚而愛民，亦三代而下，絕無而僅有者也。後之人君，擇其善者而從之，其不善者而改之，豈不交有所益乎！」這裡所說，太宗在正心修身，齊家明倫方面，有愧于二帝三王之事，主要是指太宗與其兄李建成的皇位之爭。

• 明朝官修皇帝實錄《明太祖實錄》記載，明太祖朱元璋在洪武七年八月初一日（1374年9月7日），親自前往南京歷代帝王廟祭祀三皇、五帝、夏禹王、商湯王、周武王、漢高祖、漢光武帝、隋文帝，唐太宗、宋太祖、元世祖一共十七位帝王，其中對唐太宗李世民的祝文是：「惟唐太宗皇帝英姿蓋世，武定四方，貞觀之治，式昭文德。有君天下之德而安萬世之功者也。元璋以菲德荷天佑人助，君臨天下，繼承中國帝王正統，伏念列聖去世已遠，神靈在天，萬古長存，崇報之禮，多未舉行，故于祭祀有闕。是用肇新廟宇于京師，列序聖像及歷代開基帝王，每歲祀以春、秋仲月，永為常典。今禮奠之初，謹奉牲醴、庶品致祭，伏惟神鑒。尚享！」

• 明憲宗在命儒臣訂正重刊《貞觀政要》時寫道：「太宗在唐為一代英明之君，其濟世康民，偉有成烈，卓乎不可及已。所可惜者，正心修身，有愧于二帝三王之道，而治未純也。」

• 毛澤東評價李世民說：「李世民的工作方法有四」，「自古能軍無出李世民之右者，其次則朱元璋耳。」

• 王仲犖《隋唐五代史》：「唐代的皇帝裡，唐太宗，早年的唐玄宗，唐宣宗，都是傑出的皇帝。」「我們認為舊日的封建歷史家對『貞觀之治』是渲染得有點過分的。……固然，在唐太宗統治的二十多年間，人口有了較大的增長，但比之隋極盛時戶數，還不到二分之一。」「魏徵疏文中也說到：『今自伊洛以東，暨于海岱，灌莽巨澤，茫茫千里、人煙斷絕，雞犬不聞。道路蕭條，進退艱阻。』」「封建歷史家把貞觀時期當作理想的太平盛世，和實際情況是有很大距離的。」

• 呂思勉《隋唐五代史》：「唐太宗不過中材，論其恭儉之德，及憂深思遠之資，實尚不如宋武帝，更無論梁武帝；其武略亦不如梁武帝，更無論宋武帝，陳武帝矣！」

出生年月爭議

據《貞觀政要》李世民的生日是十二月癸丑，據《資治通鑑》李世民的生日是十二月癸未，據《舊唐書》李世民生于隋開皇十八年十二月戊午（599年1月23日），因此李世民的生日應為十二月份。據《舊唐書》李世民卒年五十二歲，其弟李玄霸無考；據《新唐書》李世民卒年五十三歲，其弟李玄霸年十六歲死于隋大業十年（614年），則李玄霸生卒年為公元599－614年，而李世民生卒年為公元597－649年；李世民以十二月出生，李世民生卒年月為598年1月－649年7月，與李玄霸（599－614）為同母兄弟。《新唐書》推翻了《舊唐書》關于李世民的生卒年月，增加了李玄霸的生卒年，使李世民與李玄霸的生卒更可信。胡如雷著《李世民傳》即以《新唐書》為依據，考証李世民的出生年月為隋開皇十七年十二月戊午（598年1月28日）。

《新唐書》增加了李玄霸的生卒年歲，補正了李世民的生卒年歲，補充了《舊唐書》中沒有的珍貴史料，《新唐書》與《舊唐書》同被列為《二十四史》之欽定官史。據胡如雷考証：「李世民生于開皇十八年十二月之說亦難成立，因竇氏在不到十三個月的時間裡先後兩次生子的可能性雖然不能完全排除，但就常情而言，這種可能性也不大」。根據李世民同母弟李玄霸十六歲時死于大業十年，而倒推出李玄霸生于開皇十九年，所以若李世民生于開皇十八年十二月，則李玄霸最遲生于開皇十九年十二月，兩兄弟生辰過近，不太可能。

軼事

改名

《舊唐書·本紀第二：太宗上》記載，李世民四歲時，其父李淵任岐州刺史，有一書生自稱善相，拜訪李淵說：「公貴人也，且有貴子。」見到李世民時又說：「龍鳳之姿，天日之表，年將二十，必能濟世安民矣。」李淵害怕這話走漏，派人去追殺書生，書生卻忽然失蹤了。於是李淵就取「濟世安民」之意給李世民命名。

救駕

據新舊唐書太宗本紀，李世民十六歲時參軍，跟隨隋將雲定興，一次隋煬帝楊廣被圍，雲定興軍負責救駕，李世民獻計，故佈疑陣，嚇退敵軍，救回天子。

尚書令

由於唐太宗在即位前曾當過尚書令，故當太宗做皇帝後，大臣多不敢任其職，於是之後這個職務就幾乎不授人，尚書省的長官就只設左、右僕射，後用其他官員以「同中書門下三品」的頭銜參預朝政，執行宰相職務。至高宗時，又用低級官員以「同中書門下平章事」的頭銜參預朝政，執行宰相職務。左、右僕射成了聽令執行的官員，不能參加大政，唐中宗神龍政變復闢之後，僕射就非宰相職務。中書令、侍中在安史之亂後也不常設了。同中書門下平章事成了宰相最普遍的名稱。

武功

《大唐新語·卷一》載，太宗繼位後曾在苑囿內狩獵，一群野豬從森林中衝出。太宗舉弓四箭射殺了四隻，但還是有一頭雄野豬向馬匹直衝而來。吏部尚書唐儉慌忙下馬，與之搏鬥。太宗拔劍砍死野豬，笑著對唐儉說，「天策長史，不見上將擊賊耶？何懼之甚！」唐儉當即回答道：「漢祖以馬上得之，不以馬上理之。陛下以神武定四方，豈復逞雄心於一獸！」太宗覺得唐儉說得有理，於是停止了狩獵。

避諱

李治登基後，為了表示對他的父親李世民的無比尊敬，進行了一項重要規定，即不再使用「世」和「民」這兩個字。 這個規定導致了「觀世音菩薩」這個名字的改變，從此稱為「觀音菩薩」。在唐太宗李世民的統治時期，"觀世音菩薩"這個稱呼經常在大唐相關文獻和文化中出現。 然而，唐太宗過世後，這個稱呼變得相對不常見，逐漸淡出了歷史舞台。 這個變化反映了不同歷史時期和統治者對於宗教和文化方面的關注和偏好的變化。但也有說法認為「觀音菩薩」只是「觀世音菩薩」的簡稱。唐代清涼澄觀法師指出在梵文古本中存在兩種不同的名稱，1927年新疆出土的古抄本中，以 अवलोकितस्वर（Avalokitasvara）為觀音菩薩的名稱，證實了他的說法。「娑伐羅」（स्वर svara），意思為「聲音」，Avalokitasvara 可意譯為「觀音」，鳩摩羅什出生在西域地區，所見的應該就是這個版本。因此，觀音菩薩並非是因為避諱而出現的名稱。根據唐代玄應的說法，這可能是來自於不同地區方言所導致的。

書法

李世民酷愛書法，其書法以隸書見長，並且酷愛書法名品《蘭亭序》（即《蘭亭集序》，王羲之書法珍品，王羲之的字十分多變，就一「之」字就有十數種變化之多），相傳當年大臣蕭翼見太宗似有鬱結難紓，問之原因，知道其欲得《蘭亭序》，於是便與辯才和尚（王羲之當年墨寶輾轉傳至其七世孫智永，智永出家為僧，又將墨寶傳予其弟子辯才和尚）鬥智最後終於為李世民獲得。而王羲之本願並不想《蘭亭序》落入君王之手成為陪葬品。但最後結果事與願違，《蘭亭序》最終成為唐太宗的陪葬品。

太宗懷鷂

唐代劉餗《隋唐嘉話》載，太宗曾經飼養過一隻鷂，十分喜愛它，經常把它架在手臂上玩賞。一次看到魏徵前來奏事，就把鷂藏在了懷裡。魏徵看出端倪，匯報事情時就順勢向太宗講述古代帝王由于安逸享樂而亡國的故事，暗中勸諫太宗。魏徵奏事時故意拖了很久，鷂最終被捂死在了太宗懷裡。

文皇思女

功臣長孫順德因女兒逝世而大病。太宗認為順德系出鮮卑貴胄，身為武將卻十分挂念兒女之情，因此心生鄙夷，對房玄齡說：「順德無剛氣，因兒女牽愛而致大病，至于嗎？」。後來晉陽公主早夭，年十二，太宗非常傷心，有三十多天吃不下飯，每日哀傷數十次，因此身體急速消瘦。大臣們前來勸他，太宗回道：「朕哪裡不知道這樣悲愛無濟於事呢。我只是忍不住啊，朕也不知道為甚麼會這樣。」北宋時莊綽也說唐太宗兒女牽愛，不能自拔。

晉陽公主去世後，唐太宗下詔命令有關官員用晉陽公主封邑的余錢在公主墓旁營建佛祠，以此為公主的往生祈禱。

大臣

十八學士

• 秦王府屬杜如晦

• 秦王府記室房玄齡

• 天策府從事中郎于志寧

• 天策府軍咨祭酒蘇世長

• 天策府記室薛收

• 秦王府文學褚亮

• 國子助教陸德明

• 秦王府文學姚思廉

• 國子助教孔穎達

• 秦王府主簿李玄道

• 天策府倉曹李守素

• 秦王府記室虞世南

• 秦王府參軍蔡允恭

• 秦王府參軍顏相時

• 宋州總管府戶曹許敬宗

• 秦王府參軍薛元敬

• 國子助教蓋文達

• 秦王府咨議典簽蘇勖

凌煙閣二十四功臣

• 司徒、趙國公長孫無忌

• 故司空、揚州都督、河間元王李孝恭

• 故司空、萊國成公杜如晦

• 故司空、相州都督、太子太師、鄭國文貞公魏徵

• 司空、梁國公房玄齡

• 開府儀同三司、尚書右僕射、申國公高士廉

• 開府儀同三司、鄂國公尉遲敬德

• 特進、衛國公李靖

• 特進、宋國公蕭瑀

• 故輔國大將軍、揚州都督、褒忠壯公段志玄

• 輔國大將軍、夔國公劉弘基

• 故尚書左僕射、蔣忠公屈突通

• 故陝東道行台右僕射、鄖節公殷開山

• 故荊州都督、譙襄公柴紹

• 故荊州都督、邳襄公長孫順德

• 洛州都督、鄖國公張亮

• 光祿大夫、吏部尚書、陳國公侯君集

• 故左驍衛大將軍、郯襄公張公謹

• 左領軍大將軍、盧國公程知節

• 故禮部尚書、永興文懿公虞世南

• 故戶部尚書、渝襄公劉政會

• 光祿大夫、戶部尚書、莒國公唐儉

• 光祿大夫、兵部尚書、英國公李世勣

• 故徐州都督、胡壯公秦叔寶

宰相

• 蕭瑀（626年任尚書左僕射，627年任尚書左僕射，630年以御史大夫參議朝政，635年-636年以特進參豫朝政，643年-646年任同中書門下三品）

• 陳叔達（626年任侍中）

• 封德彞（626年－627年任尚書右僕射）

• 宇文士及（626年－627年任中書令）

• 高士廉（626年－627年任侍中，638年-643年任尚書右僕射，643年-647年任同中書門下三品）

• 房玄齡（626年－629年任中書令，629年-643年、643年-648年任尚書左僕射）

• 長孫無忌（627年－628年任尚書右僕射，645年-649年攝侍中、檢校中書令）

• 杜淹（627年－628年以吏部尚書參議朝政）

• 杜如晦（628年－629年任侍中，629年任尚書右僕射）

• 李靖（628年－629年任中書令，630年-634年任尚書右僕射）

• 王珪（628年-633年任侍中）

• 魏徵（629年－632年以秘書監參豫朝政，632年－638年任侍中，638年－642年以特進參議得失）

• 溫彥博（630年－636年任中書令，636年-637年任尚書右僕射）

• 戴冑（630年－33年以民部尚書參豫朝政）

• 侯君集（630年－632年、632年－640年以兵部尚書參豫朝政，640年－643年以吏部尚書參豫朝政）

• 楊師道（636年－639年任侍中，639年－643年、645年任中書令）

• 劉洎（639年－644年以黃門侍郎參知政事，644年-645年任侍中）

• 岑文本（642年－644年以中書侍郎專典機密，644年-645年任中書令）

• 李世勣（643年－649年任同中書門下三品）

• 張亮（643年－646年以刑部尚書參豫朝政）

• 馬周（644年－648年任中書令）

• 褚遂良（644年－647年以黃門侍郎參豫朝政，648年-649年任中書令）

• 許敬宗（645年同掌機務）

• 高季輔（645年同掌機務）

• 張行成（645年同掌機務）

• 崔仁師（648年以中書侍郎參知機務）

家庭

家世

唐太宗李世民的祖先

家族血統

唐皇室以李耳後裔自居，有出身隴西李氏與趙郡李氏兩種說法，傳統說法認為李唐皇室為漢人。在唐太宗時，曾有和尚法琳認為李唐先祖為拓跋氏之後，非李耳與隴西李氏後代，引起唐太宗不滿，被唐太宗下獄。宋代朱熹與鄭思肖以李唐閨門失禮家法繆戾，有李唐源自夷狄的說法。

其先祖李虎的兄弟名為起頭與乞豆，非漢人名字，馮承鈞與向達認為李唐家族有可能出身胡人。根據《新修本草》記載與唐太宗畫相，嚴耕望推論李世民可能擁有胡人血統。劉盼遂與王桐齡考據認為李世民家族應為鮮卑拓跋氏後裔，這個說法曾引起討論。美國學者陳三平與卓鴻澤皆認為李世民家族應出身於阿爾泰系民族，為胡人，與鮮卑拓跋部關係緊密。

根據唐朝先人曾被賜姓大野氏以及出身邊鎮等史實，日本學者金井之忠曾主張李淵家族可能出身高車叱李氏的假說，但遭陳寅恪駁斥。台灣學者劉學銚、常華安與中國學者蘇日巴達拉哈等人，皆支持李唐家族先祖應出自高車。美國漢學者歐文·拉鐵摩爾認為李世民家族具有突厥族血統。

陳寅恪認為李唐先世雖為漢人，但在李虎之後，其家族長期與胡人通婚，混有胡族血統，其祖母與其母親皆出身鮮卑，李世民本人擁有胡族血統為明確事實。中華民國學者錢穆、薩孟武與岑仲勉等人皆有類似意見。日本學者岡田英弘認為，自五胡十六國時期之後，在中國北方，漢族與胡族大量混血，特別是在山西與河北一帶，李世民家族出身在胡漢混血的北族之中。

妻妾

• 由于史料缺失，列出的後宮、姬妾諸人可能有重複。

皇后

• 文德皇后長孫氏，生廢太子（恆山愍王）李承乾、濮恭王李泰、唐高宗李治，長樂公主、城陽公主、晉陽公主、新城公主。生於隋仁壽元年（公元601年），崩於貞觀十年（公元636年），享年36歲。合葬昭陵地宮。喜愛讀書，能勸諫太宗，著有《女則》。

妃

• 貴妃韋珪，北周太傅韋孝寬曾孫女，韋圓成女。生紀王李慎、臨川公主李孟姜。尊封紀國太妃。生於公元597年，薨於公元665年，享年69歲。陪葬昭陵。與前夫李孝氏有一女，太宗封定襄縣主。

• 楊貴妃：生趙王李福，封趙國太妃。生卒年不詳。陪葬昭陵。

• 楊妃，隋煬帝女，生吳王李恪、蜀悼王李愔，生卒年不詳。墓葬不明。

• 陰妃：陰世師之女。生齊王李祐。

• 燕德妃：燕寶壽女，隋觀王楊雄外孫女。先封賢妃，後遷德妃。生越敬王李貞、江殤王李囂。封越國太妃。生於隋大業五年（公元609年），咸亨二年（公元671年），享年63歲。陪葬昭陵。

• 鄭賢妃，僅《唐會要》記載陪葬昭陵，目前尚無發現其墓葬。

• 賢妃徐惠，徐孝德女。生於武德八年（公元626年），由才人累進至二品充容。薨於永徽元年（公元650年），享年24歲。贈賢妃，陪葬昭陵石室。

嬪

• 昭儀某氏：生於隋仁壽元年（公元601年），薨於永淳元年八月二十四日（公元682年），享年81歲，十月十一日陪葬昭陵。現有昭陵墓誌一方。

• 昭容韋尼子：韋孝寬曾孫女，韋匡伯長女，韋貴妃堂妹。生於隋大業三年（公元607年），薨於顯慶元年九月八日長安崇聖宮，享年50歲，十月十八日陪葬昭陵。前夫王玄應。現有昭陵墓誌一方。

• 下嬪某氏：豫章公主母。

世婦

• 婕妤某氏：生年不詳，麟德二年卒，陪葬昭陵，墓誌《大唐故婕妤三品亡尼墓誌銘並序》。

• 楊婕妤：楊恭道第三女，生卒年不詳，墓葬不明。

• 蕭美人：蕭鑠第二女，生卒年不詳，墓葬不明。

• 崔才人：崔宏道長女，生卒年不詳，墓葬不明。

• 蕭才人：蕭鏗第二女，生卒年不詳，墓葬不明。

• 武才人（後來的武則天）：即唐高宗則天皇后武曌。武士獲女。貞觀時五品才人，後入感業寺。再入宮為高宗二品昭儀，進封為皇后，再後稱帝。

• 王帝釋：生蔣王李惲，才人。

其他妾室

• 巢剌王妃楊氏，原為齊王李元吉的王妃，玄武門之變後為太宗後宮，生曹恭王李明。有寵，太宗欲立為皇后，被魏徵勸阻。是否正式冊封為妃嬪不詳

• 刀人高惠通，李世民為秦王時的妾室

• 細人刀妙璉，李世民為秦王時的妾室

• 楊氏，隋朝尚書左右僕射、尚書令、司徒公、上柱國、楚國公楊素孫女，義陽郡太守、上柱國、清河郡開國公楊玄獎之女，唐朝宋州長史、兼虢王府司馬、上輕車都尉楊崇本姐姐，與楊貴妃是否為同一人，無考。

• 某氏，廬江王妾。

女官、宮人

• 三品亡宮周氏：三品宮人，生卒年不詳，陪葬昭陵。

• 三品亡宮金氏：武德八年（625年）出生，垂拱四年（688年）十一月二十六日卒，年六十四歲，永昌元年（689年）正月十三日陪葬昭陵，墓誌《大唐故亡宮三品尼金氏之柩》

• 亡宮五品：五品宮人，姓名不詳，生年不詳，薨於顯慶二年（657年）閏正月二十六昭陵宮，二月十四日陪葬昭陵。現有昭陵墓誌一方。

• 三品亡尼：三品宮人，姓名不詳，後出家為尼，生卒年不詳，陪葬昭陵。

• 七品典燈：生卒年不詳，姓名不詳，陪葬昭陵。

子

唐太宗共有14位兒子：

• 李承乾：母長孫皇后。生於武德元年（公元618年），卒於貞觀十九年（公元645年），年28歲。陪葬昭陵。常山郡王→中山郡王→皇太子→廢太子→贈恆山愍王

• 李寬：母不詳，早薨。生卒年不詳。嗣楚王→贈楚王

• 李恪：母隋煬帝女楊妃。生於武德二年（公元619年），薨於永徽四年二月（公元653年），享年34歲。贈司空，墓葬不詳。長沙郡王→漢王→蜀王→吳王→廢為庶人→贈鬱林郡王→吳王

• 李泰：母長孫皇后。生於武德三年（公元620年），永徽三年（公元652年）薨於鄖鄉縣，時年33歲。贈太尉、雍州牧，葬於薨地。宜都郡王→衛王→越王→魏王→東來郡王→順陽郡王→濮恭王

• 李祐：母陰妃，生年不詳，卒於貞觀十七年（公元645年）。墓葬不詳。宜陽郡王→楚王→燕王→齊王→廢為庶人

• 李愔：母隋煬帝女楊妃。生年不詳，乾封二年（667年）卒於流配地巴州。贈益州大都督，陪葬昭陵。梁王→蜀王→貶為庶人→涪陵郡王→蜀悼王

• 李惲：母王氏，生年不詳，薨上元年間。贈司空、荊州大都督，陪葬昭陵。郯王→蔣王

• 李貞：母燕德妃。生於武德八年（公元626年），薨於垂拱三年（公元688年），享年62歲。陪葬昭陵。漢王→原王→越敬王

• 李治：母長孫皇后。晉王→皇太子→唐高宗

• 李慎：母韋貴妃，生年不詳，薨於永昌元年（公元689年）。陪葬昭陵。申王→紀王

• 李囂：母燕德妃，早薨。生年不詳，卒於貞觀六年正月（公元633年）。江殤王

• 李簡：母不詳，早薨。生年不詳，卒於貞觀五年四月（公元632年）。代王

• 李福：母楊貴妃。生於貞觀八年（公元635年），薨於咸亨元年（公元670年），贈司空、并州都督，陪葬昭陵。趙王

• 李明：母李元吉妻巢剌王妃楊氏。生卒年不詳。陪葬昭陵。曹恭王

女

《新唐書》記唐太宗共有21位女兒，出生順序見于個人記載：

• 襄城公主，長女：母不明，下嫁蕭銳。生年不詳。陪葬昭陵。

• 汝南公主：第三女，母不明，早薨。生卒年不詳。墓葬不詳。

• 南平公主：母不明，下嫁王敬直，以累斥嶺南，更嫁劉玄意。生卒年不詳。陪葬昭陵。

• 遂安公主：母不明，下嫁竇逵，逵死，又嫁王大禮。生卒年不詳。陪葬昭陵。

• 長樂公主李麗質，第五女：母長孫皇后，下嫁長孫沖。生於武德四年（公元621年），薨於貞觀十七年（公元643年）八月十日，享年23歲。陪葬昭陵。

• 豫章公主：母宮中下嬪，下嫁唐義識。生卒年不詳。陪葬昭陵。

• 巴陵公主：母不明，下嫁柴令武，生年不詳，薨於永徽四年二月。墓葬不詳。

• 普安公主：母不明，下嫁史仁表，生卒年不詳，陪葬昭陵。

• 東陽公主：母不明，下嫁高履行，生卒年不詳，陪葬昭陵。

• 臨川公主，第十一或第十二女：表字「孟姜」，母韋貴妃，下嫁周道務。生於武德七年（公元624年），卒於永淳初年（公元682年），享年58歲。陪葬昭陵。

• 清河公主：名「敬」，表字「德賢」，母不明，下嫁程懷亮。生於武德七年（公元624年），卒於麟德元年（公元664年），享年41歲。陪葬昭陵。

• 蘭陵公主，第十九女：名「淑」，表字「麗貞」，母不明，下嫁竇懷悊。生年不詳，病逝於唐高宗顯慶三年（公元658年）八月。陪葬昭陵。

• 晉安公主：母不明，下嫁韋思安，又嫁楊仁輅，生卒年不詳。陪葬昭陵。

• 安康公主：母不明，下嫁獨孤謀。生卒年不詳。陪葬昭陵。

• 新興公主：母不明，下嫁長孫曦。生卒年不詳。陪葬昭陵。

• 城陽公主：母長孫皇后，下嫁杜荷，又嫁薛瓘。生卒年不詳。陪葬昭陵。

• 高陽公主：母不明，下嫁房遺愛。生年不詳，薨於永徽四年二月。墓葬不詳。

• 金山公主：母不明，早薨。生卒年不詳。墓葬不詳。

• 晉陽公主：表字「明達」，母長孫皇后，未及下嫁。生卒年不詳，薨年十二。墓葬不詳。

• 常山公主：母不明，生卒年不詳。沒有下嫁。墓葬不詳。

• 新城公主：母長孫皇后，初嫁長孫詮，後嫁韋正矩。生年不詳，薨於龍朔三年。陪葬昭陵。

繼女

• 定襄縣主李氏，韋貴妃與前夫李孝氏所生之女，嫁阿史那忠。

相關文藝作品

小說

• 《大唐秦王詞話》（［明］諸聖鄰著，又名《唐秦王本傳》、《唐傳演義》、《秦王演義》）

• 《西遊記》（［明］ 作者有爭議），描述唐王遊地府、還魂、開水陸法會的情節

• 《隋史遺文》（［明］ 袁于令著）

• 《隋唐演義》（［清］褚人獲著）

• 《說唐》（［清］ 鴛湖漁叟校訂）

• 《唐史演義》（蔡東藩著）

• 《興唐傳》（評書書目）

• 《大唐雙龍傳》（黃易著）

• 《天子傳奇4大唐威龍》（黃玉郎著）

影視作品

動漫

• 《隋唐英雄傳》(2003年)

電子遊戲

• 《軒轅劍參外傳 天之痕》(2000年)

注釋

參考資料

• 唐太宗 (維基百科)