China, a History

Although powerful in the conquest of the Wu Kingdom in 280 AD, the Jin Dynasty was severely weakened after the War of the Eight Princes from 291 to 306 AD. During Emperor Huai of Jin and Emperor Min of Jin, the country was put into grave danger with the invasion of the Xianbei tribe from the north. The sieges and ultimate sacking of Luoyang in the year 311 and Chang'an in the year 316 by invading Xianbei armies almost destroyed the dynasty. However, a scion of the royal house, Prince of Longya, fled south to salvage what was left in order to sustain the empire. Cementing their power in the south, the Jin established modern-day Nanjing (then called Jiankang) as their new capital, renaming the dynasty as the Eastern Jin (317 - 420 AD) since the new capital was located southeast of older Luoyang.

It was during the Southern and Northern Dynasties period that southern China (below the Yangtze River) was greatly developed from its previous state of early Chinese colonization and settlement. Beforehand, the south was inhabited by small and isolated communities of Chinese in a vast uncolonized wilderness of non-Chinese tribes, starting as a near peripheral frontier and changing into a thriving, urbanized, sinicized region of China. In his book Buddhism in Chinese History, Arthur F. Wright points out this fact by stating:

When we speak of the area of the Yangtze valley and below in the period of disunion, we must banish from our minds the picture of the densely populated, intensively cultivated South China of recent centuries. When the aristocrats of the remnants of the Chin [Jin] ruling house fled to the Nanking [Nanjing] area early in the fourth century, the south contained perhaps a tenth of the population of China. There were centers of Chinese culture and administration, but around most of these lay vast uncolonized areas into which Chinese settlers were slow to move.