In 317, Sima Rui, a member of the royal clan, was proclaimed emperor under the support of Wang Dao and set up his capital in Jiankang (today's Nanjing, Jiangsu province). This is known as Eastern Jin Dynasty in history. In the north, the minorities who had moved inward and Han set 16 authorities in the Yellow Rover basin, which is called the "16 States".

In the lateter half of the fourth century, Fu Jian, the ruler of the Former Qin Dynasty, united the north. In 383, Fu Jian led an army south hoping to wipe out Eastern Jin in one attack. Before the war, some people firmly advised against Fu Jian doing so, arguing that Eastern Jin Dynasty, with Yangtze River as a natural barrier, was very difficult to attack. Fu Jian insisted and sid, "We will overwhelm with numerical strength, so long as every one of us throws a whip into Yangtze River, its water can not keep flowing!"

Facing the attack from the Former Qin Dynasty's army, Eastern Jin Dynasty decided to make concerned efforts to fight against the enemy. At that time, the leaders of Jin army were Xie Shi, Xie Xuan and Liu Laozhi. They had an army of only 80,000 soldiers. In the 10th lunar month Fu Jian's army captured Shouyang (today's Shouxian county, Anhui province). Fu Jian sent Zhu Xu, a Jin general captured by the Former Qin army, to Jin army to induce them to capitulate. Seizing the chance of going to Jin camp, Zhu Xu told Xie Shi that there were only 250,000 Former Qin soldiers in the front line, and he suggested Jin army launch an attack first.

In the 11th month, Liu Laozhi attacked the Former Qin army with 5,000 crack soldiers and wiped out 50,000 Former Qin soldiers. Xie Shi and other general advanced on the crest of the victory and confronted the Former Qin army with each army on one side of Feishui River. One day, Xie Xuan proposed that it was not convenient for the two belligerent parties to fight on different sides of the river, and asked the Former Qin army to draw back. Fu Jian had planned to attack Jin army with his cavalry when they crossed the river, so he ordered his army to retreat. However, his soldiers did not known the real meaning of the retreat, and many of them thought that they had lost the battle. Just at that time, Zhu Xu shouted loudly, "Qin's army has lost the battle!" This threw the Former Qin's soldiers into great confusion at once. Jin army took advantage of the occasion and crossed Feishui River. Fu Jian's soldiers fled desperately and Fu Jian himself got wounded by an arrow. At last, Fu Jian returned to Chang'an with only a little more than 100,000 soldiers.

This was the famous Battle of Feishui in history, in which a small army defeated a big one. After the Battle of Feishui, the Former Qin Dynasty fell, and North China was again rent by independent regimes. Eastern Jin ensured stablity in the south. Later, Jin's authority was taken by the general Liu Yu who founded Song Dynasty. During the 170 years from 420 to 589, the south went through four dynasties, namely, Song, Qi, Liang and Chen, historically know as Southern Dynasties. In 439, Northern Wei Dynasty unified the northern regimes, and entered into a confrontational situation with Southern Dynasties. Thus, the history entered a period known as Northern and Southern Dynasties.