What conditions made the rise of the Sui and Tang dynasties possible? Why didn’t such a change happen a century earlier?
Both the Sui and Tang dynasties were able to unite China under common rule following a period of disunity and rebellion by strict enforcement of their rule by ruthless means. The Han dynasty might have lasted longer; however there was tremendous infighting and jealousy within the ruling elite which prevented effective leadership. Also, large landowners had used their influence to gain larger tracts of land and also reduce their own tax burden. The tax burden was therefore necessarily levied on the peasants, who could not afford it. This condition together with a large number of deaths from epidemic diseases resulted in widespread dissension, notably the Yellow Turban Revolt. Leading war lords ultimately forced the emperor from power, and China was again divided.
Huang Jin, the first Sui ruler, was able to unite China by sending strong military forces throughout the area and forcing them to submit to his rule. Early Tang rulers, like the Sui, tended to be ruthless in imposing rule on China. This had been absent during the last days of the Han Dynasty when inner dissension prevented effective centralized rule.