Liu Yu founds the Liu Song dynasty

Liu Yu (363–422) came from an impoverished family at Jingkou (modern Zhenjiang) that traced its descent from a younger brother of the founder of the Han. Around 399 he joined the army of Liu Laozhi — the Beifu force whose troops had won the battle of the Fei River — and made his name against the rebellion of Sun En. In 404 he led the rising against the warlord Huan Xuan, who had forced Emperor An of Jin to yield him the throne, and restored the Jin. As master of the court he conquered the Southern Yan in Shandong in 410 and in 417 took Chang’an and ended the Later Qin, although the city was lost to the Xia of Helian Bobo the following year.

In 418 Liu Yu had himself made Duke of Song. Emperor An died in January 419, killed on Liu Yu’s orders according to the histories, and his brother, Emperor Gong, was put on the throne. In the summer of 420 Liu Yu came to Jiankang; his aide Fu Liang drafted an edict of abdication, which the emperor copied out in his own hand on red paper, remarking, according to the Book of Jin, that the Jin had lost the realm long ago and he had nothing to regret, and on 7 July he moved out of the palace to his residence. On the dingmao day of the sixth month, 10 July 420, Liu Yu mounted the altar in the southern suburb, announced his accession to Heaven and changed the era name to Yongchu. The former emperor was made Prince of Lingling and was murdered the next year.

Liu Yu reigned for less than two years and died in 422. The Liu Song lasted until 479, when it gave way to the Southern Qi; followed by the Liang and the Chen, the Southern dynasties kept Jiankang as their capital until 589. The founding of the Liu Song in 420 is taken as the beginning of the period of the Northern and Southern dynasties.