Sui Dynasty Unifies China
In 581, a general named Yang Jian seized the throne of the Northern Zhou state and proclaimed the Sui dynasty, taking the name Emperor Wen. Within a decade he had conquered the rival southern regime and ended a long era of fragmentation. Although the dynasty itself lasted only about thirty-seven years, it rebuilt the foundations of a unified Chinese empire and set the stage for the long-lived Tang dynasty that followed.
The background was centuries of division. After the Han dynasty collapsed in the early third century, China split into competing kingdoms and short-lived dynasties. Non-Han peoples from the steppe established states across the north, while a succession of Han Chinese courts ruled from Nanjing in the south. The "four hundred years" of division in the popular summary is a round figure; the Western Jin reunited much of the country briefly in 280, but that unity soon collapsed in civil war and invasion. Yang Jian came from a powerful northern aristocratic network that blended Chinese and steppe elites, and he gained power as a regent and father-in-law to a child emperor of Northern Zhou before taking the throne himself.
Wen consolidated his position quickly. He moved the capital to a new planned city, Daxing, near present-day Xi'an, and reformed government by streamlining administration and strengthening central control over appointments. He promoted a land distribution system, standardized laws and coinage, and began shifting recruitment toward examinations and merit, an ancestor of the later imperial examination system, though its early form was limited. In 589 Sui armies crossed the Yangtze and overran the Chen dynasty, the last southern regime, bringing the whole country under one ruler.
Wen's son Yangdi, who took power in 604, pursued enormous projects. Most famous was the Grand Canal, which linked the Yangtze and Yellow River regions and eventually the area near modern Beijing. Some segments were built or expanded earlier under Wen, and the great push came under Yangdi, using the labor of vast numbers of conscripted workers. The canal helped move grain from the productive south to the political centers of the north, and it became a vital artery for centuries.
The costs were heavy. Yangdi's canal-building, palace construction, and repeated, costly campaigns against Goguryeo in Korea strained the population and the treasury. Revolts broke out, and in 618 Yangdi was assassinated. One of his former officials, Li Yuan, founded the Tang dynasty, inheriting much of the Sui administrative framework, roads, and canal. Traditional Chinese histories, written by successor dynasties, tend to portray Yangdi harshly, and modern historians often credit the Sui with laying groundwork for the golden age that followed.