Abstract：Niyang county in Beidi prefecture of Han dynasty is near Ning county of Gansu province, but the historical record of HouHanShu shows that Niyang county of Beidi prefecture should be the territory of Yao county, Shanxi province.Based on the comparison between two versions of Niyang counties, we can conclude that Niyang county migrated to Yao county of Shanxi pronvince after the invasion of Qiang ethnic minority during Wei-Jin dynasty, then, Niyang county had its own territory in Yao county, which makes people confuse them.

Keyword：Han Dynasty;Niyang county;original place;