what caused the collapse of the han dynasty
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.
Fall of the Western Roman Empire The Fall of the Western Roman Empire (also called Fall of the Roman Empire or Fall of Rome) was the process of decline in the Western Roman Empire in which it failed to enforce its rule, and its vast territory was divided into several successor polities. The Roman Empire lost the strengths that had allowed it to exercise effective control over its Western provinces; modern historians mention factors including the effectiveness and numbers of the army, the health and numbers of the Roman population, the strength of the economy, the competence of the Emperors, the internal struggles for power, the religious changes of the period, and the efficiency of the civil administration. Increasing pressure from barbarians outside Roman culture also contributed greatly to the collapse. The reasons for the collapse are major subjects of the historiography of the ancient world and they inform much modern discourse on state failure.[1][2]