After the Western Jin was vanquished, the Han government withdrew to the east. In 317, Sima Rui, a member of the Western Jin imperial family stationed in Jiankang (now Nanjing in Jiangsu), re-established the Jin government, which became known as the Eastern Jin. The power of Eastern Jin only covered southern part of China. In northern part, more than 20 reigns were set up by different minorities on the Central Plains, Which was known later as "Period of Five Ethnic Minorities and Sixteen States".
In the Eastern Jin period, the development of powerful family politics reached its peak as royal power was on the decline. Depending the support of the southern bureaucrats and gentry-officials, Sima Rui could become emperor. The early years of the Eastern Jin saw a stable period after the suppression of Wang Dun and Su Jun. Four powerful families - the Wang, the Xie, the Yü and the Huan - successively dominated the politics of the Jin Court.The powerful families made their efforts to run their southern farms. Many northern families moved south and brought with them advanced production techniques. Immigrants from the north and the local peasants in the south worked hard to cultivate this vast wilderness. All these promoted the development of the southern part of China.
The Eastern Jin was full of internal conflicts. The immigrant northern landlords and southern landlords ostracized each other. Zu Di, a southern gentry-official, once led an expeditionary force north and regained the Yellow River valley for a short time. Afterwards, most of the gentry-officials in power advocated northern expeditions so as to increase their family prestige. Among them, three northern expeditions led by Huan Wen are the best known. His armies took Luoyang, entered Guanzhong and reached Hebei. But he did not consolidate these victories. In 383, the Former Qin, which was a dynasty unified the northern part of China, it army marched southward to attack Eastern Jin. The army of Former Qin and army of Eastern Jin met at Feishui (today's Feihe, Anhui Province). With Chancellor Xie An devising strategies, Xie Shi and Xie Xuan leading the troops utterly defeated the Former Qin force and won a decisive victory at the Battle of Feishui. After this battle, the Former Qin declined quickly. But this relief from external threat was followed by a series of internal disturbances. First, Sun En and Lu Xun launched rebellions. Then Huan Xuan won the civil war and usurped the throne. Later, General Liu Yu of the Beifu troops suppressed the peasant uprisings and gained prestige through a number of northern expeditions. At last, he established his own dynasty Song Dynasty to replace the Eastern Jin in southern part of China in 420.