In the second century C.E. the Han government suffered a series of blows. A succession of child emperors required regents to rule in their place until they reached maturity, allowing the families of empresses to dominate the court. Emperors, once grown, turned to eunuchs (castrated palace servants) for help in ousting the empresses’ families, only to find that the eunuchs were just as difficult to control. In 166 and 169 scholars who had denounced the eunuchs were arrested, killed, or banished from the capital and official life. Then in 184 a millenarian religious sect rose in massive revolt. The armies raised to suppress the rebels soon took to fighting among themselves. In 189 one general slaughtered two thousand eunuchs in the palace and took the Han emperor captive. After years of fighting, a stalemate was reached, with three warlords each controlling distinct territories in the north, the southeast, and the southwest. In 220 one of them forced the last of the Han emperors to abdicate, formally ending the Han Dynasty.

The period after the fall of the Han Dynasty is often referred to as the Age of Division (220–589). A brief reunification from 280 to 316 came to an end when non-Chinese who had been settling in north China since Han times seized the opportunity afforded by the political turmoil to take power. For the next two and a half centuries, north China was ruled by one or more non-Chinese dynasties (the Northern Dynasties), and the south was ruled by a sequence of four short-lived Chinese dynasties (the Southern Dynasties) centered in the area of the present-day city of Nanjing.

In the south a hereditary aristocracy entrenched itself in the higher reaches of officialdom. These families intermarried only with families of equivalent pedigree and compiled lists and genealogies of the most eminent families. They saw themselves as maintaining the high culture of the Han and looked on the emperors of the successive dynasties as upstarts — as military men rather than men of culture. In this aristocratic culture the arts of poetry and calligraphy flourished, and people began collecting writings by famous calligraphers.

Establishing the capital at Nanjing, south of the Yangzi River, had a beneficial effect on the economic development of the south. To pay for an army and to support the imperial court and aristocracy in a style that matched their pretensions, the government had to expand the area of taxable agricultural land, whether by settling migrants or converting the local inhabitants into taxpayers. The south, with its temperate climate and ample supply of water, offered nearly unlimited possibilities for such development.

The Northern Dynasties are interesting as the first case of alien rule in China. Ethnic tensions flared from time to time. In the late fifth century the Northern Wei (way) Dynasty (386–534) moved the capital from near the Great Wall to the ancient city of Luoyang, adopted Chinese-style clothing, and made Chinese the official language. But the armies remained in the hands of the non-Chinese Xianbei tribesmen. Soldiers who saw themselves as marginalized by the pro-Chinese reforms rebelled in 524. For the next fifty years north China was torn apart by struggles for power. It had long been the custom of the northern pastoral tribes to enslave those they captured; sometimes the residents of entire cities were enslaved. In 554, when the city of Jiangling was taken, a hundred thousand civilians were enslaved and distributed to generals and officials.