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.
List of emperors of the Han dynasty
At times, especially when an infant emperor was placed on the throne, a regent, often the empress dowager or one of her male relatives, would assume the duties of the emperor until he reached his majority. Sometimes the empress dowager's faction—the consort clan—was overthrown in a coup d'état. For example, Empress Lü Zhi (d. 180 BC) was the "de facto" ruler of the court during the reigns of the child emperors Qianshao ("r". 188–184 BC) and Houshao ("r". 184–180 BC). Her faction was overthrown during the Lü Clan Disturbance of 180 BC and Liu Heng was named emperor (posthumously known as Emperor Wen). Before Emperor Wu died in 87 BC, he had invested Huo Guang (d. 68 BC), Jin Midi (d. 86 BC), and Shangguan Jie (上官桀)(d. 80 BC) with the power to govern as regents over his successor Emperor Zhao of Han ("r". 87–74 BC). Huo Guang and Shangguan Jie were both grandfathers to Empress Shangguan (d. 37 BC), wife of Emperor Zhao, while the ethnically-Xiongnu Jin Midi was a former slave who had worked in an imperial stable. After Jin died and Shangguan was executed for treason, Huo Guang was the sole ruling regent. Following his death, the Huo-family faction was overthrown by Emperor Xuan of Han (r. 74–49 BC), in revenge for Huo Guang poisoning his wife Empress Xu Pingjun (d. 71 BC) so that he could marry Huo's daughter Empress Huo Chengjun (d. 54 BC).