End of the Han dynasty
The end of the Han dynasty refers to the period of Chinese history from 189 to 220 AD, which roughly coincides with the tumultuous reign of the Han dynasty's last ruler, Emperor Xian. During this period, the country was thrown into turmoil by the Yellow Turban Rebellion (184–205). Meanwhile, the Han Empire's institutions were destroyed by the warlord Dong Zhuo, and fractured into regional regimes ruled by various warlords, some of whom were nobles and officials of the Han imperial court. Eventually, one of those warlords, Cao Cao, was able to gradually reunify the empire, ostensibly under Emperor Xian's rule, but the empire was actually controlled by Cao Cao himself. Cao Cao's efforts to completely reunite the Han empire were rebuffed at the Battle of Red Cliffs in 208 / 209, when his armies were defeated by the allied forces of Sun Quan and Liu Bei. The Han dynasty formally ended in 220 when Cao Cao's son and heir, Cao Pi, pressured Emperor Xian into abdicating in his favour. Cao Pi became the emperor of a new state, Cao Wei. A year later, in response to Cao Pi's usurpation of the Han throne, Liu Bei declared himself emperor of Shu Han; and in 229, Sun Quan followed suit, declaring himself emperor of Eastern Wu. The period from Emperor Xian's abdication in 220 to the partial reunification of China under the Jin dynasty in 265 was known as the Three Kingdoms era in Chinese history.
Chu–Han Contention
The Chu–Han Contention (206–202 BC) was an interregnum between the Qin dynasty and the Han dynasty in Chinese history. Following the collapse of the Qin dynasty in 206 BC, Xiang Yu split the former Qin Empire into the Eighteen Kingdoms. Two major contending powers emerged, Western Chu and Han, which engaged in a struggle for supremacy over China. Western Chu was led by Xiang Yu, while the Han leader was Liu Bang. Several minor kings also warred, but these were largely independent of the main conflict between Western Chu and Han. The war ended in 202 BC with total victory for Han, with Liu Bang soon proclaiming himself first emperor of the Han dynasty.