 Erzhu Tianguang's father was a cousin of Erzhu Rong, who was a Northern Wei general and the chief of the ethnic Xiongnu Qihu (契胡) tribe.In Erzhu Tianguang's youth, he was described to be resolute and capable in archery and horseriding.Erzhu Rong considered him a close confidant, and often discussed military matters with him.