 These states then immediately began fighting each other, inaugurating the chaotic and bloody Sixteen Kingdoms era.After the fall of Chang'an in 316, the Western Jin dynasty collapsed, forcing survivors of the Jin monarch under Sima Rui to flee south of the Yangtze River to Jiankang (modern Nanjing) and establish the (317–420).The Eastern Jin dynasty, though under constant threats from the north, remained relatively stable for the next century, but was eventually usurped by general Liu Yu in 420 and replaced with the Liu Song (420–479).