IN 493, Emperor Xiaowen set out with300,000 troops, from the Northern Wei Dynasty(386-534)capital of Pingcheng (present-day Datong,Shanxi)on a southern expedition,The emperor,called Tuoba Hong, was then 26 years old. In this lifetime he ruled only half of China;his place in Chinese history is by virtue of his efforts to assimilate ethnic groups into the Han majority,advancing China's establishment as a muliethnic nation.