Juqu Mengxun
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 (馬權), 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 (蘭門山, near Zhangye) on a vacation day, but submitting a false report through the official Xu Xian (許咸) 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.