The Han dynasty ruled China from 206 B.C. to 220 A.D. The new emperor maintained a legalist ideology just like the Qin dynasty but also had ideas of Confucianism to have a centralized system showing benevolence. After eighty years, Emperor Wu of Han launched a period of military expansion. The Han armies controlled many territories, including Silk Road in Mongolia and Xinjiang. The Silk Road  helped make a political, economic, military, and culture center, but it was very expensive to manage and further expansion was cut off.  Several factors contributed to the fall of the Han dynasty, including uprisings of desperate and hungry people, the spread of attacks by nomadic groups, and official corruption.