Under Later Liang and Duan Ye

Juqu Mengxun was born in 368, while the area that would later be his domain was under the rule of Former Liang, but little is known about his early years. He was of Xiongnu ancestry, and it was said that his ancestors served as the left Juqu (an office title of unclear responsibility) for Xiongnu Chanyus, and so they started using Juqu as the family name. Later, during Former Qin and Later Liang rule, Juqu Mengxun became known for broad knowledge in history and military tactics and thought to be both humorous and full of strategies, and became feared by the Former Qin governor Liang Xi (梁熙) and the Later Liang emperor Lü Guang, and so he tried to divert attention from himself by drinking heavily and spending time on frivolous matters.

In 397, Lü Guang sent his brother Lü Yan (吕延) on an attack against Western Qin, but Lü Yan was killed in a trap set by the Western Qin prince Qifu Gangui. Juqu Mengxun's uncles Juqu Luochou (沮渠罗仇) and Juqu Quzhou (沮渠麴粥) were Lü Yan's assistants, and in light of Lü Yan's death, Lü Guang believed false accusations against them and executed them. Juqu Mengxun escorted their caskets back to their home territory of Zhangye (张掖, in modern Zhangye, Gansu) and then persuaded the various Xiongnu tribes to rise against Later Liang. Initially, he was defeated by Lü Guang's son Lü Zuan and fled into the mountains, but he was soon joined in rebellion by his cousin Juqu Nancheng (沮渠男成), who sieged Jiankang (建康, also in modern Zhangye) and persuaded Duan Ye the governor of Jiankang Commandery to accept leadership of the rebels, establishing Northern Liang. Soon, Lü Guang came under the greater threat of a rebellion by Guo Nen (郭黁) and recalled Lü Zuan to face that threat, and Duan Ye's nascent state survived. Juqu Mengxun joined Duan Ye, and was made a major general of the state. In 398, Duan Ye sent him on an expedition against Lü Guang's nephew Lü Chun (吕纯), and Juqu Mengxun captured Lü Chun, causing all remaining Later Liang cities west of Zhangye to submit to Northern Liang, further enlarging Northern Liang territory. Duan Ye therefore created Juqu Mengxun the Marquess of Linchi. Lü Guang's son Lü Hong (吕弘) soon abandoned Zhangye, and Duan Ye moved his capital to Zhangye, and tried to further pursue Lü Hong against Juqu Mengxun's advice. Lü Hong defeated him and nearly killed him, but Juqu Mengxun saved Duan Ye. In 399, when Duan Ye claimed the title of Prince of Liang, he made Juqu Mengxun one of his two prime ministers, sharing responsibilities with Liang Zhongyong (梁中庸). Later that year, when Northern Liang was under attack by Lü Guang's crown prince Lü Shao and Lü Zuan, it was at Juqu Mengxun's suggestion that Duan Ye refused to engage, forcing Lü Shao and Lü Zuan to retreat when Southern Liang relief forces under Tufa Lilugu arrived. In 400, when the general Wang De (王德) rebelled, Duan Ye sent Juqu Mengxun to attack him, and Juqu Mengxun defeated him and, while he fled, captured his wife and children.

By 401, however, Duan Ye was heavily apprehensive of Juqu Mengxun's strategies and abilities, and he considered sending Juqu Mengxun far away. Juqu Mengxun, knowing Duan Ye's suspicions, tried to hide his ambitions. However, at the same time, because he was often insulted by another official that Duan Ye heavily relied on, Ma Quan (马权), he falsely accused Ma of treason, and Duan Ye killed Ma. Juqu Mengxun then told Juqu Nancheng that he felt that Duan Ye lacked abilities and was an inappropriate ruler, trying to persuade Juqu Nancheng to rise against Duan Ye. When Juqu Nancheng refused, Juqu Mengxun requested to leave the capital to be the governor of Xi'an Commandery (西安, also in modern Zhangye), and Duan Ye agreed. Juqu Mengxun then set a trap for both Juqu Nancheng and Duan Ye—he made an appointment with Juqu Nancheng to offer sacrifices to the god of Lanmen Mountain (兰门山, near Zhangye) on a vacation day, but submitting a false report through the official Xu Xian (许咸) that Juqu Nancheng was set to rebel and would start the rebellion on a day that he requested permission to sacrifice to the god of Lanmen Mountain. When Juqu Nancheng requested Duan Ye for such permission, Duan Ye arrested him and ordered him to commit suicide. Juqu Nancheng, who had realized Juqu Mengxun's plan by this point, told Duan Ye that this was a sign that Juqu Mengxun was about to rebel and that he should keep Juqu Nancheng alive, and then when Juqu Mengxun rebels he could counterattack. Duan Ye, not believing in Juqu Nancheng, executed him. Juqu Mengxun then cited Duan Ye's execution of Juqu Nancheng to ask his people to rise against Duan Ye, and the people indeed rose in rebellion, because of the high regard they had for Juqu Nancheng. The rebels quickly arrived at Zhangye, and it fell. Despite Duan Ye's pleas, Juqu Mengxun executed him. The Northern Liang officials all endorsed Juqu Mengxun to take over the throne, and he took throne with the title Duke of Zhangye.

Early reign

Juqu Mengxun, having taken the ducal title, promoted a number of officials who were considered capable, and it was said that the people of his state were pleased. He also nominally submitted to the Later Qin emperor Yao Xing as a vassal, although remaining in reality independent. However, he immediately faced the crisis that his Jiuquan (酒泉) and Liangning (凉宁) Commanderies (roughly modern Jiuquan, Gansu) rebelled against him and joined Western Liang. He became fearful, and he sent his brother Juqu Ru (沮渠挐) the Marquess of Dugu and official Zhang Qian (张潜) to meet Yao Xing's uncle Yao Shuode (姚硕德), who had just recently sieged Later Liang's capital Guzang (姑臧, in modern Wuwei, Gansu) and forced the Later Liang emperor Lü Long to submit, offering to surrender his state to Later Qin. Yao Shuode was pleased, but upon return to Northern Liang, while Zhang recommended such surrender, Juqu Ru argued against it, and Juqu Mengxun, while remaining nominally a Later Qin vassal, executed Zhang and never actually surrendered his state. He also tried to make peace with Southern Liang's prince Tufa Lilugu, initially sending his son Juqu Xi'nian (沮渠奚念) as a hostage to Southern Liang, but Tufa Lilugu rejected Juqu Xi'nian, stating that he was too young to be a meaningful hostage and demanding Juqu Ru instead. After initially refusing, Juqu Mengxun gave in to Southern Liang demands after Tufa Lilugu defeated him in battle.

In 402, with Guzang under a severe famine, Juqu Mengxun attacked Later Liang, causing Lü Long to seek aid from Southern Liang, but before Southern Liang forces could arrive, Lü Long defeated Juqu Mengxun, and Juqu Mengxun made peace with Lü Long, offering him food for famine relief.

Around the new year 403, Liang Zhongyong, who continued to be a key official after Juqu Mengxun took over for Duan Ye, fled from his domain and joined Western Liang's prince Li Gao. Rather than killing Liang's wife and children as might be expected, Juqu Mengxun sent them to Liang, commenting, "I treated Liang like a brother, but he did not trust me. He did not betray me, but himself; I do not mind losing a man."

Later that year, because Juqu Mengxun and Tufa Lilugu were constantly attacking him and draining his state's resources, Lü Long felt he could not maintain his state any more, and he surrendered his state (now constiting of little more than Guzang) to Later Qin. He also persuaded the Later Qin general Qi Nan (齐难) to attack Juqu Mengxun, but Juqu Mengxun repelled Qi's attack and then made peace with Qi. Juqu Mengxun sent Juqu Ru (who must have somehow been returned from Southern Liang by this point) to the Later Qin capital Chang'an to declare his submission to Yao Xing. Later that year, having received reports that his two uncles and generals Juqu Qinxin (沮渠亲信) and Juqu Kongdu (沮渠孔笃) were corrupt and harmful to the people, he forced to commit suicide. Meanwhile, he accepted the title that Yao Xing created him, the Marquess of Xihai, to show submission, despite his initial displeasure that Tufa Lilugu's brother and successor Tufa Rutan was created a duke while he was only created a marquess.

In 405, Li Gao moved his capital from Dunhuang (敦煌, in modern Dunhuang, Gansu) to Jiuquan, to be closer to Zhangye to exert pressure on Juqu Mengxun.

In spring 406, Tufa Rutan launched a major attack on Northern Liang, but Juqu Mengxun was able to hold Zhangye, forcing Tufa Rutan to withdraw. In fall 406, Juqu Mengxun made a surprise attack on Jiuquan, initially defeated Li Gao, but he could not successfully siege Jiuquan and was forced to withdraw.

In fall 407, Tufa Rutan made another attack on Northern Liang, but Juqu Mengxun was able to defeat him.

In 410, Tufa Rutan and his brother Tufa Juyan (秃发俱延) launched successive attacks on Northern Liang, and Juqu Mengxun was not only able to repel them, but then proceeded to siege Guzang (where Tufa Rutan had moved his capital after receiving it as a bestowmen from Yao Xing in 406). The people of Guzang, because Tufa Rutan had previously carried out massive executions after a failed rebellion, collapsed in fear, and more than 10,000 households surrendered to Northern Liang. Tufa Rutan, apprehensive of both Juqu Mengxun and a rebellion by Zhequ Qizhen (折屈奇镇) in the south, made peace with Juqu Mengxun and moved his capital back south to Ledu (乐都, in modern Haidong Prefecture, Qinghai). As soon as he left Guzang, however, Hou Chen (侯谌) and Jiao Lang (焦朗) seized control of Guzang and nominally submitted to Juqu Mengxun, although they held Guzang themselves. In fall 410, Juqu Mengxun attacked Western Liang and defeated Li Gao's heir apparent Li Xin and captured the Western Liang general Zhu Yuanhu (朱元虎), and he subsequently made peace with Li Gao when Li Gao ransomed Zhu with silver and gold.

In spring 411, with Jiao Lang still holding Guzang, Juqu Mengxun sieged Guzang and captured him, but pardoned him. He left Juqu Ru in command at Guzang and then attacked Southern Liang, putting Ledu under siege, and only withdrew after Tufa Rutan sent his son Tufa Anzhou (秃发安周) as a hostage. Tufa Rutan soon counterattacked, however, and initially was successful, but Juqu Mengxun trailed Tufa Rutan's forces and defeated him, again putting Ledu under siege and forcing Tufa Rutan to send another son, Tufa Ran'gan (秃发染干) as a witness before withdrawing. In fall 411, Juqu Mengxun made a surprise attack on Western Liang, but was unsuccessful, and as he ran out of food supplies and withdrew, Li Gao sent Li Xin to attack him, defeating him.

In winter 412, Juqu Mengxun moved the capital from Zhangye to Guzang, and he claimed the greater title of Prince of Hexi.

Middle reign

In 413, Juqu Mengxun created his son Juqu Zhengde (沮渠政德) heir apparent. In the summer of that year, he repelled another attack from Tufa Rutan, and then again put Ledu under siege for 20 days, but could not capture it. He renewed the attack when Tufa Rutan's general Tufa Wenzhi (秃发文支) surrendered to him, forcing Tufa Rutan to send Tufa Juyan as a hostage to him.

Also in 413, while Juqu Mengxun was sleeping, his eunuch Wang Huaizu (王怀祖) tried to assassinate him, but only hurt his foot. Juqu Mengxun's wife Princess Meng arrested Wang and had him beheaded. Also in 413, Juqu Mengxun's mother Lady Che died.

With Western Qin having destroyed Southern Liang in 414, Northern Liang and Western Qin began to have a series of wars, with Juqu Mengxun largely winning these battles against Western Qin's prince Qifu Chipan. In 416, after an inconclusive battle, Northern Liang and Western Qin entered into peace.

In 417, Juqu Mengxun tried to lay a trap for Li Xin (who had succeeded Li Gao after Li Gao's death that year) by having his general Juqu Guangzong (沮渠广宗) pretending to surrender to Western Liang, while Juqu Mengxun lay in wait. However, Li Xin realized the trap and withdrew, and as Juqu Mengxun gave chase, Li Xin defeated him.

That year, Juqu Mengxun became fearful and angry when he heard that the Jin general Liu Yu had destroyed Later Qin and seized its territory, probably in fear that Liu Yu would next advance against his state. When his official Liu Xiang (刘祥) was making a report to him with a smile, Juqu Mengxun angrily stated, "How do you dare to smile upon hearing that Liu Yu had entered Hangu Pass!" and beheaded Liu Xiang. (This is despite Juqu Mengxun having made an overture in 415 agreeing to submit to Jin as a vassal.) His fears appeared to subside after Liu Yu left former Later Qin territory late in 417, and dissipate completely when the Xia emperor Helian Bobo crushed troops under Liu Yu's son Liu Yizhen (刘义真) in 418.

In 418, Juqu Mengxun made an attack on Western Liang, but Li Xin refused to engage him, and he withdrew. Later that year, he submitted to Jin as a vassal.

In 420, Juqu Mengxun set another trap for Li Xin. He pretended to attack Western Qin's city Haomen (浩亹, in modern Haidong Prefecture, Qinghai), but once reaching Haomen, immediately withdrew and hid his army at Chuanyan (川岩, near Zhangye). Li Xin, believing wrongly that Juqu Mengxun's defenses were down, decided to attack Zhangye, against the advice of Song Yao and Zhang Tishun, as well as his mother Princess Dowager Yin. As he approached Zhangye, Juqu Mengxun intercepted him and defeated him. His generals then advised him to quickly withdraw to Jiuquan, but Li Xin, stating that he had disobeyed his mother and would only be able to see her again after a victory, engaged Juqu Mengxun again, suffering an even greater defeat, and he was killed in battle. Juqu Mengxun quickly captured Jiuquan and most of Western Liang territory. He largely maintained a policy of trying to pacify the Western Liang people and incorporating capable Western Liang officials into his administration, including Li Gao's half-brother Song Yao (宋繇). In winter 420, Li Xin's brother Li Xun seized Dunhuang and tried to reestablish Western Liang rule, and Juqu Mengxun initially sent Juqu Zhengde to siege Dunhuang. In spring 421, he attacked Dunhuang himself, and when Li Xun tried to surrender, he refused. Li Xun's official Song Cheng (宋承) rebelled and offered the city to him, and Li Xun committed suicide, ending Western Liang; contrary to the pacification policy he carried out at Jiuquan, Juqu Mengxun slaughtered the populace of Dunhuang.

With Western Liang destroyed, Juqu Mengxun renewed his attacks against Western Qin, and while his initial attacks were repelled, his attacks had a draining effect on Western Qin, whose strength began to be sapped. At some point, he also encouraged Tufa Rutan's crown prince Tufa Hutai (秃发虎台) to rebel against Western Qin, promising to lend him two commanderies and troops, but after Tufa Hutai's plot, which also included his sister Princess Tufa (Qifu Chipan's wife), was discovered, Qifu Chipan had Tufa Hutai and Princess Tufa executed. Some members of the Tufa clan fled to Northern Liang.

In 421, the general Tang Qi (唐契), a former Western Liang general and brother-in-law to Li Xin, rebelled at his post of Jinchang (晋昌, in modern Jiuquan, Gansu), and not until 423 did Juqu Zhengde defeat Tang, but Tang and his brother Tang He (唐和) and nephew Li Bao (李宝, Li Xin's son) fled to Yiwu (伊吾, in modern Kumul Prefecture, Xinjiang) and held out there.

Also in 423, Juqu Mengxun sent tributes to Jin's successor state, Liu Song, which Liu Yu had established in 420. Liu Yu's son Emperor Shao of Liu Song affirmed Juqu Mengxun's title of Prince of Hexi. In fall of that year, when Rouran attacked Northern Liang, Juqu Mengxun sent Juqu Zhengde to fight Rouran, but Juqu Zhengde was defeated and killed. Juqu Mengxun then created his next son Juqu Xingguo (沮渠兴国) as heir apparent.

In 426, a decisive battle would largely end Western Qin as a threat to Northern Liang. Qifu Chipan and his crown prince Qifu Mumo were launching a major attack on Northern Liang. Juqu Mengxun sent messengers to persuade the Xia emperor Helian Chang (Helian Bobo's son and successor) to make a surprise attack on the Western Qin capital Fuhan (枹罕, in modern Linxia, Gansu). Helian Chang, in response, sent his general Hulu Gu (呼卢古) to attack Wanchuan and Wei Fa (韦伐) to attack Nan'an (南安, in modern Dingxi, Gansu), and while Western Qin was able to hold Wanchuan, Nan'an fell, at great loss. In winter 426, Xia forces commanded by Hulu and Wei attack Fuhan, forcing Qifu Gangui to move the capital to Dinglian (定连, also in Linxia), and Hulu and Wei then captured another important Western Qin city, Xiping (西平, in modern Xining, Qinghai), and while they then withdrew, Western Qin had been dealt a major blow. Later that year, with Emperor Taiwu of Northern Wei having in turn defeated Helian Chang in battle, capturing Chang'an and nearly capturing the Xia capital Tongwan (统万, in modern Yulin, Shaanxi) as well, Juqu Mengxun sent messengers to Northern Wei offering to submit as a vassal.

In 428, when Qifu Chipan died and was succeeded by Qifu Mumo, Juqu Mengxun made a major attack on Western Qin. Qifu Mumo sent back his general Juqu Chengdu (沮渠成都), whom Qifu Chipan captured in 422, to seek peace, and they entered into a peace agreement. However, just several months later, Juqu Mengxun renewed his attacks on Western Qin.

Late reign

In 429, Juqu Mengxun launched another major attack on Western Qin, but during the campaign, Juqu Xingguo was captured, and Juqu Mengxun was forced to withdraw, after his forces, aligned also with Tuyuhun forces commanded by Murong Muliyan (慕容慕利延), the brother of the khan Murong Mugui (慕容慕璝). He soon sent a large amount of grain to Qifu Mumo, requesting to ransom Juqu Xingguo, but Qifu Mumo refused, so Juqu Mengxun created Juqu Xingguo's younger brother, by the same mother, Juqu Puti (沮渠菩提), to be heir apparent. (Qifu Mumo kept Juqu Xingguo as an official and married a sister to him.)

In 431, with Xia's emperor Helian Ding (Helian Chang's brother and successor after Helian Chang was captured by Northern Wei in 428) having first destroyed Western Qin and killed Qifu Mumo and then having been defeated and captured by Murong Mugui), Juqu Mengxun, now with his territory directly in contact with Northern Wei, sent his son Juqu Anzhou to Northern Wei as a hostage to show his loyalty. In response, Northern Wei's Emperor Taiwu sent his official Li Shun (李顺) to Northern Liang to bestow a number of high titles, including the title of Prince of Liang.

By 432, Juqu Mengxun, in his old age, was said to be arbitrary and cruel, with his subjects suffering the pain henceforth. When Li Shun again arrived in his territory, he initially refused to bow down to receive the Northern Wei emperor's edict, but upon Li Shun's warning that such disrespect will be punished, did so. In 433, he grew ill, and his nobles and officials believed Juqu Puti to be too young to succeed him, and so deposed Juqu Puti and replaced him as heir apparent with his older brother Juqu Mujian. Juqu Mengxun soon died, and Juqu Mujian succeeded him.

Era names

• Yong'an (永安 yǒng ān) 401–412

• Xuanshi (玄始 xuán shǐ) 412–428

• Chengxuan (承玄 chéng xuán) 428–430

• Yihe (义和 yì hé) 430–433

Personal information

• Mother

　• Lady Che (d. 413)

• Wife

　• Princess Meng

• Children

　• Juqu Zhengde (沮渠政德), the Heir Apparent (created 413, killed in battle by Rouran forces 423)

　• Juqu Xingguo (沮渠兴国), the Heir Apparent (created 423), later captured and detained by Western Qin's prince Qifu Mumo 429 (d. 431)

　• Juqu Puti (沮渠菩提), the Heir Apparent (created 429, deposed 433)

　• Juqu Mujian (沮渠牧犍), the Heir Apparent (created 433), later prince

　• Juqu Wuhui (沮渠无讳), later prince

　• Juqu Anzhou (沮渠安周), later prince

　• Juqu Yide (沮渠仪德)

　• Juqu Bing (沮渠秉) (brothers forced by Emperor Taiwu of Northern Wei to kill him 444)

　• Juqu Donglai (沮渠董来)

　• Princess Xingping, later consort to Emperor Taiwu of Northern Wei (forced to commit suicide 447)

　• Another daughter, older than Juqu Mujian

出身

沮渠原是匈奴官名，分为左沮渠与右沮渠。沮渠蒙逊出身匈奴贵族，为卢水胡领袖。

生平

复仇起兵

沮渠蒙逊博览史籍，知晓天文，才智出众又有谋略，为人圆滑又灵活变通，故前秦将领如梁熙及吕光都对其才能既感惊异，亦生畏惧。沮渠蒙逊知道后亦常饮酒出游，故作低调。前秦亡后，蒙逊一族依附吕光建立的后凉。397年，蒙逊伯父后凉尚书沮渠罗仇和三河太守沮渠麴粥随从后凉进攻西秦的乞伏乾归，吕光弟吕延轻敌，兵败被杀，后凉军被迫撤退。吕光以败军之罪杀罗仇、麴粥二人，蒙逊在宗族聚集参加二人丧礼的机会举众叛凉，斩后凉中田护军马邃及临松令井祥与众盟誓，十日之间就招合了万多人，屯兵金山。同年，蒙逊堂兄沮渠男成拥立段业称凉州牧，建北凉，蒙逊附之，获授镇西将军、张掖太守。

屡见智谋

398年，蒙逊深知西郡战略价值高，遂大力支持段业进攻该郡的决定，并受命进攻。然而蒙逊攻郡城十馀日不下，改为引水灌城，终逮获太守吕纯而返，晋昌郡王德及敦煌郡孟敏战后皆向北凉归降。蒙逊以功封为临池侯。同年后凉张掖守将吕弘率众弃城东归，蒙逊以「归师勿遏，穷寇弗追」为理反对段业追击，但段业不听，终为吕弘所败，段业更因蒙逊才得安全撤退，因而叹道：「我没有听从子房的话，才会有此结果！」后蒙逊又反对段业以将领臧莫孩担任新建西安城的太守，称臧莫孩「勇而无谋，知进忘退」，必会失败。段业又不听，不久臧莫孩就被后凉吕纂击败。天玺元年（399年），段业称凉王，以蒙逊为尚书左丞。不久，后凉太子吕绍及吕纂来攻，段业请得南凉秃发乌孤派杨轨等救援，就打算迎击，蒙逊就说：「杨轨恃著骑兵战力强，有伺机图谋我们的意图。而吕绍和吕纂在死地，肯定会与我们决战以求生。拒绝对战将有如泰山般安稳，出战则像叠起的蛋一样危险。」段业同意，遂按兵拒绝接战，后凉军没有办法，亦退兵。

兵变登位

虽然蒙逊屡次建言协助段业，但却害怕对方容不下自己，所以每每特意不显露自己的智谋。段业也畏惧蒙逊的能力，故此调蒙逊为临池太守，改以门下侍郎马权为张掖太守。马权得段业信任和重用，其人亦有过人军事谋略，却轻视并常欺侮蒙逊，令蒙逊对他又恨又怕，于是向段业进言中伤马权，却令段业将马权杀死。蒙逊随后向沮渠男成建议除去段业，改奉男成为主，但被男成拒绝。蒙逊心中不安，自求外任西安太守，也得段业批准。

不过蒙逊天玺三年（401年）四月约男成一同去祭告兰门山（甘肃省山丹县西南）时，暗中派人告诉段业说男成准备发动变乱，段业斩男成，男成死前对段业说：「蒙逊早就和臣说过他要叛乱了，只是臣以兄弟缘故才不说出来。蒙逊以臣还在，怕部众不听从他，于是约臣与其祭山，反派人诬告臣。臣若果死了，蒙逊肯定很快就起兵了。请假称臣死了，宣告臣的罪行，蒙逊肯定会起兵叛乱，而臣立即就会讨伐他，必会成功。」段业不听。蒙逊以此为藉口出兵攻段，并进屯侯坞，段业急派右将军田昂、武威将军梁中庸反击蒙逊，田昂、梁中庸至侯坞反降蒙逊，五月，蒙逊大军抵张掖（今甘肃张掖西北），田昂侄子田承爱开城门内应，蒙逊入城，杀段业，遂称大都督、大将军、凉州牧、张掖公，改年号永安。

后秦亦在永安二年（402年）任命沮渠蒙逊为镇西将军、沙州刺史、西海侯。蒙逊登位后提拔人才，得文武官员支持。

攻夺姑臧

蒙逊曾经送子沮渠奚念到南凉做人质，想与其结好，然而南凉主秃发利鹿孤嫌奚念年幼，要求改以蒙逊弟沮渠挐为质。蒙逊写信表示不愿，竟惹怒利鹿孤并遭进攻，蒙逊唯有答应利鹿孤的要求。永安七年（407年），秃发傉檀率兵五万进攻蒙逊，蒙逊于均石击败傉檀，并进攻南凉西郡太守杨统。永安十年（410年），蒙逊因之前南凉枯木及胡康攻掠临松而攻南凉，至显美强迁数千户人退兵。傉檀率兵追击，并在穷泉追上蒙逊，蒙逊大败傉檀，更乘胜攻至姑臧，万多户姑臧人民向蒙逊归降。蒙逊随后接受傉檀求和，迁八千多户人离开。傉檀不久就迁都至乐都，焦朗等人乘势据姑臧自立，蒙逊遂率三万兵进攻，夺取了姑臧。412年，蒙逊迁都姑臧，称河西王，改元玄始。

消灭西凉

西凉在沮渠蒙逊杀段业登位前一年自立，蒙逊曾于永安十一年（411年）轻兵袭击西凉，西凉君主李暠闭门拒战，蒙逊撤兵时更被西凉世子李歆击败。至玄始六年（417年）李歆即位，蒙逊命张掖太守沮渠广宗诈降西凉，李歆中计出兵迎接但及后却发现蒙逊所领的三万伏兵而撤走，蒙逊追击却在鲜支涧一战中大败予李歆。蒙逊一度想重结败兵再战，但为沮渠成都劝止，在增筑建康城后班师。玄始九年（420年），李歆乘蒙逊攻西秦浩亹的机会进攻，蒙逊闻讯时正自浩亹回师至川岩，于是发布浩亹已下，即将进攻黄谷的假消息，让李歆以为蒙逊仍在外，实质正暗中回援。李歆果然继续进攻，两军遂于怀城决战，李歆兵败但不肯撤退，坚持再战，于是在蓼泉再败并被杀。蒙逊因而乘势攻陷西凉都城酒泉，灭亡了西凉。次年，蒙逊率军进攻李恂领导之西凉残馀势力所据的敦煌，成功攻陷，彻底灭亡西凉势力。

交结宋魏

朱龄石灭蜀后曾与蒙逊有使者往来，蒙逊亦上表表示其臣服于东晋，晋廷亦授予凉州刺史。玄始十年（421年），把持东晋军政的刘裕代晋建南朝宋后，于十月任命沮渠蒙逊为使持节、散骑常侍、都督凉州诸军事、镇军大将军、开府仪同三司、凉州刺史、张掖公。玄始十二年（423年）二月，蒙逊遣使南朝宋，宋廷进蒙逊侍持节、开府、侍中、都督凉秦河沙四州诸军事、骠骑大将军、领护匈奴中郎将、西夷校尉、凉州牧，河西王。玄始十五年（426年）五月又获改授车骑大将军。承玄四年（431年），蒙逊又曾命人出使北魏，更派儿子沮渠安周入魏，北魏遂命其为假节，侍中，都督凉州西域羌戎诸军事，太傅，行征西大将军，凉州牧，凉王。

义和三年（433年），蒙逊去世，享年六十六，諡武宣王，庙号太祖。因他生前所立继承人沮渠菩提年幼，贵族拥立其年长之子沮渠牧犍继位。

性格特徵

沮渠蒙逊有军事才能，故屡次向段业提供意见助其解兵厄，亦让其国能立于河西诸国间。登位后，蒙逊伯父中田护军沮渠亲信及临松太守沮渠孔笃骄横奢侈，侵害人民，蒙逊说：「祸乱我国家的就是两位伯父呀，还怎治理百姓呀！」于是命二人自杀《晋书·载记第二十九》：「蒙逊伯父中田护军亲信、临松太守孔笃并骄奢侵害，百姓苦之。蒙逊曰：『乱吾国者，二伯父也，何以纲纪百姓乎！』皆令自杀。」。不过他用计陷害堂兄男成，接著攻杀他推举的段业，令《晋书》评价他「见利忘义，苞祸灭亲。」蒙逊知刘裕灭后秦的消息后十分愤怒，门下校郎刘详其时有事报告，蒙逊却回应：「你知道刘裕入关，竟敢这样得意！」就将刘详杀了，亦见其严酷残暴一面《晋书·载记第二十九·沮渠蒙逊传》：「蒙逊闻刘裕灭姚泓，怒甚。门下校郎刘祥言事于蒙逊，蒙逊曰：『汝闻刘裕入关，敢研研然也！』遂杀之。其峻暴如是。」。

据《晋书》所载，蒙逊颇信天象，并写其多次凭天象指引而胜利《晋书·载记第二十九》：「太史令刘梁言于蒙逊曰：『辛酉，金也。地动于金，金动刻木，大军东行无前之徵。』时张掖城每有光色，蒙逊曰：『王气将成，百战百胜之象也。』遂攻秃发西郡太守杨统于日勒。」《晋书·载记第二十九》：「太史令张衍言于蒙逊曰：『今岁临泽城西当有破兵。』蒙逊乃遣其世子政德屯兵若厚坞。蒙逊西至白岸，谓张衍曰：『吾今年当有所定，但太岁在申，月又建申，未可西行。且当南巡，要其归会，主而勿客，以顺天心。计在临机，慎勿露也。』遂攻浩亹，而蛇盘于帐前。蒙逊笑曰：『前一为腾蛇，今盘在吾帐，天意欲吾回师先定酒泉。』烧攻具而还，次于川岩。闻李士业徵兵欲攻张掖，蒙逊曰：『入吾计矣。但恐闻吾回军，不敢前也。兵事尚权。』」《晋书·载记第二十九》：「（蒙逊）顾谓左右曰：『古之行师，不犯岁镇所在。姚氏舜后，轩辕之苗裔也。今镇星在轩辕，而裕灭之，亦不能久守关中。』」。亦有载蒙逊曾祭祀西王母寺，并命中书侍郎张穆为寺内的《玄石神图》作赋，铭于寺前；蒙逊又曾派世子沮渠兴国到南朝宋借《周易》等书，又曾向南朝宋司徒王弘求《搜神记》《宋书·卷九十八》：「世子兴国遣使奉表，请《周易》及子集诸书，太祖并赐之，合四百七十五卷。蒙逊又就司徒王弘求《搜神记》，弘写与之。」。沮渠蒙逊曾在母车太后病重时引咎于己，同时大赦死罪以下，车太后仍然去世。当旱灾时，他也有同样举动，次日就下大雨了。

逸事

蒙逊亦信佛，其时有一名自西域东来的僧人昙无谶在凉州译经，又「以男女交接之术教授妇人」，时蒙逊诸女及子媳都信奉他。昙无谶亦通术数和咒术，屡次准确说出其他国家的事，沮渠蒙逊遂奉昙无谶为国师，每以国事谘之。后北魏听闻昙无谶的事迹，要求蒙逊将昙无谶送到北魏，蒙逊不肯，及后还将他杀了。

家庭

妻

• 孟王后

子女

• 沮渠政德，413年立为继承人，423年对柔然军作战阵亡

• 沮渠兴国，423年立为继承人，429年被西秦天王乞伏暮末俘虏拘押，431年卒

• 沮渠牧犍，433年立为继承人，后为天王

• 沮渠菩提，沮渠兴国同母弟，429年立为继承人，433年废黜

• 沮渠无讳，后为天王

• 沮渠安周，后为天王

• 沮渠仪德

• 沮渠秉，444年被北魏太武帝所杀

• 沮渠董来

• 沮渠奚念，曾被派去南凉为质子，为秃发利鹿孤拒绝

• 兴平公主，后为北魏太武帝右昭仪，447年被赐死

• 某女，沮渠牧犍姐