Though the three kingdoms were reunited temporarily in 278 by the Jin Dynasty , the contemporary non-Han Chinese ( Wu Hu , 五胡) ethnic groups controlled much of the country in the early 4th century and provoked large-scale Han Chinese migrations to south of the Chang Jiang . In 303 the Di people rebelled and later captured Chengdu , establishing the state of Cheng Han . Under Liu Yuan the Xiongnu rebelled near today's Linfen County and established the state of Han Zhao . His successor Liu Cong captured and executed the last two Western Jin emperors. Sixteen kingdoms were a plethora of short-lived non-Chinese dynasties that came to rule the whole or parts of northern China in the 4th and 5th centuries. Many ethnic groups were involved, including ancestors of the Turks , Mongolians , and Tibetans . Most of these nomadic peoples had to some extent been "Sinicized" long before their ascent to power. In fact, some of them, notably the Ch'iang and the Xiong-nu, had already been allowed to live in the frontier regions within the Great Wall since late Han times.

Southern and Northern Dynasties ( 420 AD - 589 AD )

A limestone statue of the Bodhisattva , from the Northern Qi Dynasty , 570 AD, made in what is now modern Henan province. Main article: Southern and Northern Dynasties

Signaled by the collapse of East Jin (東晉/东晋) Dynasty in 420, China entered the era of the Southern and Northern Dynasties. The Han people managed to survive the military attacks from the nomadic tribes of the north, such as the Xian Bei (鮮卑), and their civilization continued to thrive.

In Southern China, fierce debates about whether Buddhism should be allowed to exist were held frequently by the royal court and nobles. Finally, near the end of the Southern and Northern Dynasties era, both Buddhist and Taoist followers compromised and became more tolerant of each other.

In 589, Sui (隋) annexed the last Southern Dynasty, Chen (陳/陈), through military force, and put an end to the era of Southern and Northern Dynasties.

The Sui Dynasty (隋朝), which managed to reunite the country in 589 after nearly four centuries of political fragmentation, played a role more important than its length of existence would suggest. The Sui brought China together again and set up many institutions that were to be adopted by their successors, the Tang. Like the Qin, however, the Sui overused their resources and collapsed. Also similar to the Qin, traditional history has judged the Sui somewhat unfairly. As it has stressed the harshness of the Sui regime and the arrogance of its second emperor, giving little credit for the Dynasty's many positive achievements.