War of the Eight Princes

In the early Western Jin, Emperor Wu, Sima Yan, believed that Cao Wei had been usurped by the Sima because it had weakened its imperial princes, leaving the throne isolated. He therefore enfeoffed many kin as kings and sent them to garrison important regions such as Xuchang, Ye and Chang'an. These princes commanded troops and also ran local civil government, and their power grew. Emperor Wu died in AD 290, and the crown prince Sima Zhong took the throne as Emperor Hui, who was feeble-minded and incompetent. Empress Jia Nanfeng seized power and struggled for control with the consort-clan figure Yang Jun. In 291 the empress joined Sima Wei, Prince of Chu, to kill Yang Jun, then killed Sima Liang, Prince of Runan, and the Prince of Chu, setting off years of war among the princes. The main contenders were the eight princes: Sima Liang of Runan, Sima Wei of Chu, Sima Lun of Zhao, Sima Jiong of Qi, Sima Ai of Changsha, Sima Ying of Chengdu, Sima Yong of Hejian and Sima Yue of Donghai, known as the “War of the Eight Princes.” Sima Lun of Zhao once deposed Emperor Hui and took the throne, and the princes called in troops of the Xiongnu, Xianbei and other peoples who had moved inward. The fighting centered on Luoyang and ended only in 306 when Sima Yue took control, lasting sixteen years. The disaster was immense: the price of rice soared to 10,000 cash per shi, the population of the Central Plains died in great numbers, and survivors fled, hundreds of thousands to the south. The war drained the Western Jin's strength and sent it into rapid decline; the chiefs of the peoples who had moved inward took the chance to rise, the Western Jin soon fell, and the north entered a long division.