Before reign

Not much is known about Duan Ye's life before 397. He was from Jingzhao Commandery (京兆, roughly modern Xi'an, Shaanxi), and was probably a low-level official that Former Qin sent to Liang Province (凉州, modern central and western Gansu) after conquering Former Liang in 376. His wife and children remained in Jingzhao.

The first historical reference to Duan Ye was in 388, when he was one of the officials under the ruler of Later Liang, Lü Guang, then carrying the title the Duke of Jiuquan. At a feast, Lü Guang and his officials were discussing his administration, when Duan Ye told Lü Guang that he was being overly harsh in his application of laws. Lü Guang, citing the examples of the legalists Wu Qi and Shang Yang, defended his harsh applications. Instead of backing down, Duan Ye pointed out that Wu and Shang both died as a result of their use of laws, and that what Lü Guang was doing was not in accordance of the wishes of the people. Lü Guang solemnly apologized. (However, what this conversation revealed about Duan Ye's own personal philosophy on governance may demonstrate the reasons why he was later ineffective as a ruler.)

In 396, when Lü Guang claimed the greater title of Prince of Sanhe, he made Duan Ye one of his ministers.

In 397, by which time Lü Guang, then with imperial title, was facing a rebellion from Juqu Mengxun and Juqu Nancheng after listening to false accusations and executing their uncles Juqu Luochou and Juqu Quzhou (沮渠麴粥), Duan Ye was the governor of Jiankang Commandery (建康, in modern Zhangye, Gansu). Juqu Nancheng put Jiankang under siege, but sent messengers to try to persuade Duan Ye that the Later Liang regime was becoming so corrupt as to be nearing destruction, and that with Duan's talents, he should be a leader. Duan Ye initially refused, but after 20 days of siege, no aid came from the Later Liang capital Guzang (姑臧, in modern Wuwei, Gansu). Duan Ye's advisors suggested that he accept Juqu Nancheng's proposal, and Duan Ye, who was also apprehensive of Lü Guang's officials Fang Gui (房晷) and Wang Xiang (王详), with whom he had inimical relationships, agreed. He took the title the Duke of Jiankang and changed era name, signifying a declaration of independence from Later Liang and the establishment of Northern Liang. He entrusted most important affairs of state to Juqu Nancheng.

Reign

Lü Guang's son Lü Zuan soon arrived and attacked Jiankang, but could not capture it. Soon thereafter, with the sorcerer Guo Nen (郭黁) having rebelled at Guzang, Lü Zuan withdrew from Jiankang, allowing Duan Ye's nascent state to stand.

In 398, Duan Ye sent Juqu Mengxun to attack Xi Commandery (西郡), in modern Zhangye, Gansu), and Juqu Mengxun captured it and its governor, Lü Guang's nephew Lü Chun. Soon thereafter, Jiuquan (酒泉, roughly modern Jiuquan, Gansu) and Dunhuang (敦煌, roughly modern Dunhuang, Gansu) Commanderies submitted as well, allowing Northern Liang to take over a large portion of formerly Later Liang territory. Lü Guang's son Lü Hong then also withdrew from Zhangye (张掖, in modern Zhangye), and Duan Ye moved his capital from Jiankang to Zhangye to further pressure Later Liang. He trailed Lü Hong to try to attack him, against Juqu Mengxun's advice not to cut off Lü Hong's escape, and was defeated by Lü Hong, saved from destruction only by Juqu Mengxun.

In 399, Duan Ye claimed the title of Prince of Liang. He made Juqu Mengxun and Liang Zhongyong (梁中庸) key ministers.

In summer 399, Lü Zuan and Lü Guang's heir apparent Lü Shao jointly attacked Northern Liang. Duan Ye sought aid from Southern Liang's prince Tufa Wugu, and Tufa Wugu sent his brother Tufa Lilugu and the general Yang Gui to assist him. Duan Ye, because of the Southern Liang aid, was set to make a counterattack against Later Liang forces, but Juqu Mengxun persuaded him that doing so would give Southern Liang an opening to make a surprise attack, and so Duan Ye merely defended, and Lü Shao and Lü Zuan were forced to withdraw.

In summer 400, Lü Zuan, who had by that point become Later Liang's emperor, made a major attack against Northern Liang, putting Zhangye under siege. However, Southern Liang's general Tufa Rutan then made a major attack on Guzang, forcing Lü Zuan to withdraw.

Also in 400, Duan would lose a major part of his territory. When his governor of Dunhuang Commandery, Meng Min (孟敏) died that year, the officials in Dunhuang Commandery supported Li Gao, a county magistrate, as his successor. Duan Ye initially agreed, but was then warned by his general Suo Si (索嗣) that Li Gao had greater ambitions and should not be permitted to stay at Dunhuang. Duan Ye therefore sent Suo to be the governor of Dunhuang. Li Gao made a surprise attack against Suo and defeated him, and then demanded that Suo be executed. At the advice of Juqu Nancheng (who also disliked Suo), Duan Ye executed Suo and apologized to Li Gao, who briefly remained submissive. However, late in 400, Li Gao, along with Tang Yao (唐瑶), seceded with six commanderies, establishing Western Liáng, and Li Gao soon took over modern western Gansu and eastern Xinjiang.

In 401, Duan Ye, apprehensive of Juqu Mengxun's military abilities, demoted him and replaced him with Ma Quan, but soon believed Juqu Mengxun's false accusations against Ma and executed him. Juqu Mengxun then proposed to Juqu Nancheng that Duan Ye be killed and replaced with Juqu Nancheng—citing Duan Ye's lack of judgment and ability to govern and that with Suo and Ma dead, there would be no one to oppose them if they made a move against Duan Ye. Juqu Nancheng refused, stating that such an action would be unjust.

Juqu Mengxun then set a trap for both Juqu Nancheng and Duan Ye. He set a date 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.

In a last-ditch effort, Duan Ye released the general Tian Ang (田昻), whom he had suspected of treachery earlier and imprisoned, and put Tian in charge of an army against Juqu Mengxun, along with Liang Zhongyong. Tian, however, quickly surrendered to Juqu Mengxun, and Duan Ye's remaining troops collapsed. Zhangye fell, and despite Duan Ye's pleas, Juqu Mengxun executed him and took over the throne.

Era names

• Shenxi (神玺 shén xǐ) 397–399

• Tianxi (天玺 tiān xǐ) 399–401

生平

获推为主

段业博览史传，有文辞才学，原是前秦将领吕光部将杜进僚属，从征西域。后吕光建后凉，出任建康太守。后凉龙飞二年（397年），沮渠蒙逊叛后凉，其堂兄沮渠男成亦叛，并进攻段业所守的建康。男成派使者劝段业支持自己，段业最初不肯，但在男成围困二十日后还是答应了，遂被推为大都督、龙骧大将军、凉州牧、建康公，改年号神玺。

神玺元年（397年）以沮渠男成为辅国将军、沮渠男成的堂弟沮渠蒙逊为张掖太守，委以军国重任。

猜忌蒙逊

神玺二年（398年），段业在沮渠蒙逊的支持下，力排众议命蒙逊进攻西郡，终擒太守吕纯，随后晋昌太守王德及敦煌太守孟敏都向段业投降。不久段业又攻吕弘镇守的张掖，吕弘率兵弃城东归，段业不听沮渠蒙逊归师勿遏、穷寇勿追的谏言，执意追击，终大败而还。神玺三年（399年），称凉王，改元天玺。同年后凉太子吕绍及吕纂来攻，段业请得秃发乌孤派杨轨等协助，就打算进攻结阵迎战的后凉军。蒙逊却认为杨轨伺机图谋北凉，而且后凉军兵处死地，肯定会奋战求生，故段业不要出战，免陷入危机。段业同意，最终按兵不战，后凉军也退兵。

段业本来只是一个有德望的儒者，因缘际会被推上王位，其实本人并没有权谋，无法约束下属，只信任卜卦、巫术。而一直以来，段业对于沮渠蒙逊的勇略就颇为忌惮，最初就让沮渠蒙逊由尚书左丞外调到临池郡任太守，想疏远他。段业又亲近信任门下侍郎马权，以其代替蒙逊张掖太守之位，但蒙逊怨恨马权常轻侮自己，于是向段业中伤马权，段业遂杀马权。另段业因索嗣认为李暠不能留在敦煌，任由其发展其势力的建议而派索嗣接替李暠任敦煌太守，然李暠击败了索嗣，并上请段业诛杀索嗣，段业在沮渠男成劝告下就将索嗣杀了。此时，蒙逊有除掉段业之意，遂和男成表示既马权、索嗣二人已死，应当杀死段业，改奉男成为主，但为男成拒绝。蒙逊因段业忌惮自己而愈见不安，遂自请任西安太守，段业亦怕蒙逊很快会反叛，答应了其请求。

公元400年（天玺二年）十一月，酒泉太守王德背叛北凉，自称为河州刺史。段业派沮渠蒙逊带兵前去征讨。王德烧毁了酒泉城，带领部队投奔李暠之亲家唐瑶。沮渠蒙逊在沙头追上，把他们打得大败，俘虏了王德的妻子儿女和部落居民之后才回去。

奸佞所误

天玺三年（401年），沮渠蒙逊诬沮渠男成谋反，段业收捕沮渠男成并命其自杀，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。」可是，段业没有听信。男成死后，沮渠蒙逊以此为藉口激怒将士，并率领他们攻击段业，连羌胡都起兵响应。段业见此就让田昂及梁中庸率兵攻蒙逊，当时将领王丰孙警告称西平田氏世代都有反叛者，而田昂「貌恭而心狠，志大而情险」，并不可信；但段业自以只能倚仗他对抗蒙逊，还是没有听从。最终田昂果然临阵降于蒙逊，梁中庸亦被逼投降。接著田昂侄田承爱在蒙逊兵临张掖时让蒙逊入城，段业左右溃散，段业请求蒙逊饶他一命，让其东归与妻儿见面，但蒙逊还是杀了他。沮渠蒙逊随后获推为张掖公，继立为北凉君主。

注释