Jin Zhun was an official of the Chinese/Xiongnu state Han Zhao, who in 318 staged a coup against the Han Zhao emperor and his son-in-law Liu Can and then massacred the imperial Liu family. His forces were subsequently squeezed in by the succeeding emperor Liu Yao and the general Shi Le, and, facing probable defeat, his followers assassinated him. He was probably ethnically Chinese, but that is not completely clear, some sources also indicate that he was of Xiongnu origin.
During Liu Cong's reign
The first reference to Jin Zhun in history was in 315, when he was mentioned as a minor Han Zhao general, whose two beautiful daughters Jin Yueguang and Jin Yuehua were taken by the Han Zhao emperor Liu Cong as consorts. Liu Cong, who was then starting the highly unorthodox practice of creating multiple empresses, creating Jin Yueguang as "Upper Empress" and Jin Yuehua as "Right Empress." That same year, Upper Empress Jin was revealed by the official Chen Yuanda as having committed adultery, causing Liu Cong to feel compelled to depose her. Ashamed, she committed suicide. It was also mentioned that another daughter of Jin Zhun married Liu Cong's son, Liu Can, but the year is unknown. As years went by, Jin Zhun became closely associated with the Liu Can and several eunuchs and servants trusted by Liu Cong and Liu Can, including Wang Chen, Xuan Huai, and Guo Yi. Jin and Guo were instrumental in persuading Liu Can that his uncle, Liu Ai the crown prince was conspiring against him and his father, and subsequently participated heavily in Liu Can's plot to have his uncle falsely accused of treason and removed as crown prince in 317. Jin also assassinated the former Crown Prince Ai, on Liu Can's orders. Liu Can became crown prince, and Princess Jin became crown princess.
Coup against Liu Can
After Liu Cong died in summer 318, Liu Can succeeded to the throne, and proceeded to spend day and night committing adultery with his father's four surviving empresses -- one of which was Jin Zhun's daughter Jin Yuehua. Jin hatched a plan to overthrow Liu Can, and managed to persuade, with the help of his two daughters that several imperial princes and high-level officials were conspiring against him. With Liu Can's approval, those imperial princes and high-level officials were executed. Jin Zhun became in control of government, and, after putting his cousins Jin Ming and Jin Kang in command of the armies, carried out a coup against Liu Can, capturing and executing him. He then massacred all members of the imperial Liu clan that he could capture -- regardless of gender or age. He also dug up the graves of Liu Cong and the founding emperor, Liu Yuan, and burned the Han Zhao imperial temple.
After the coup
Jin claimed for himself the titles of supreme commander and either "heavenly prince" or "great prince" of Han. He acted in the role of an emperor, and he sent messengers to Emperor Yuan of Jin, claiming that he was about to revert to Jin Dynasty's rule. The Jin emperor believed him, and sent out an army to try to support him. Before that Jin army could come close to arriving, however, Jin Zhun was caught in a trap. The major Han Zhao generals Liu Yao the Prince of Qin, who controlled the Chang'an region, and Shi Le, who controlled the eastern empire, both moved their troops against him. Shi Le, whose headquarters were closer at Xiangguo, quickly arrived near the capital Pingyang, but chose to not engage Jin Zhun immediately. In winter 318, Liu Yao, a cousin of Liu Cong, declared himself emperor, and advanced on Pingyang as well. Jin was caught between Liu Yao's and Shi's forces. Jin sent imperial garments and wagons to Shi, seeking peace. Shi, however, sent those, along with Jin's messenger, over to Liu Yao. Liu Yao claimed that he admired Jin for carrying out the coup that allowed him to be emperor, because the government had become so corrupt late in Liu Cong's and in Liu Can's reigns, and offered not only to spare his life but to continue to allow him to be an important official. Jin, however, distrusted Liu Yao's offer, because he had killed Liu Yao's mother and brother in the massacre. However, as he hesitated, he was assassinated by cousins Jin Ming and Jin Kang, Qiao Tai, and Wang Teng, who then surrendered to Liu Yao, who then massacred the Jin clan.