Han Dynasty Falls
In 220 AD, Cao Pi, son of the warlord Cao Cao, forced the last Han emperor, Emperor Xian, to abdicate and proclaimed himself emperor of a new dynasty, Wei. This act ended a imperial line that had ruled China for roughly four centuries, apart from a brief interruption under Wang Mang. It also opened the Three Kingdoms period, in which Wei, Shu, and Wu competed for supremacy. The Han left a deep imprint on Chinese identity: the majority ethnic group still calls itself the "Han people," and the dynasty became a model of imperial unity.
The Han had been weakening for decades. From the second century, court politics were dominated by struggles among palace eunuchs, empresses' families, and scholar-officials, and child emperors were common. Heavy taxation, land concentration among powerful families, and natural disasters left many peasants in distress. In 184 the Yellow Turban Rebellion, inspired by a religious movement, swept across the north and east. Though the rebels were eventually suppressed, the government relied on regional commanders to do so, and these men gained armies and independence that the court could no longer control.
Political authority collapsed further when the general Dong Zhuo seized the capital in 189 and later moved the court, leaving Luoyang heavily damaged. Warlords then fought over the north. Cao Cao eventually took custody of Emperor Xian around 196 and ruled in his name, defeating his main rival Yuan Shao at Guandu around 200. His push south, however, was halted at the Battle of Red Cliffs around 208, where the forces of Sun Quan and Liu Bei resisted him. That setback helped entrench a three-way division.
After Cao Cao died in 220, Cao Pi took the final step of ending the Han in name as well as in fact. Liu Bei, a claimant to Han descent, declared himself emperor of Shu Han in 221 in the southwest, and Sun Quan took the title of emperor of Wu in 229 in the southeast. Later popular culture, above all the Ming-era novel Romance of the Three Kingdoms, turned these rivalries into legend, though it heavily dramatizes and fictionalizes events recorded in the more sober history by Chen Shou.
The era did not end the idea of a unified China, but reunification was slow and fragile. Wei was succeeded by the Jin dynasty in 266, which conquered Wu in 280, yet it soon fractured amid civil war and northern invasions. China remained largely divided until the Sui reunified it in 589. The period often called the "four centuries of division" is a loose label, since there were interludes of unity, but it saw major population movements southward, the spread of Buddhism, and the growth of powerful aristocratic families that shaped later Chinese society.