How did Xianbei's surname come from? Where did Xianbei people move after Wu Huan's surrender to the Han Dynasty during the reign of Emperor Wu of the Han Dynasty?

Xianbei is one of the northern nomadic tribes in ancient China. At the end of the 3rd century BC, after the Huns broke Donghu, they moved to Xianbei Mountain, beyond the Great Wall in Liaodong, hence taking the mountain name as their clan name. During the period of Emperor Wu of the Han Dynasty, Wu Huan descended to the Han Dynasty, moved south to the Laoha River basin, and Xianbei also pushed southwest, living in the present Xilamulun River basin.