Liu Bobo was born in 381, when his father Liu Weichen (劉衛辰) was an important Xiongnu chief and a vassal of Former Qin. It is not known whether his mother Lady Fu was Liu Weichen's wife or concubine. He was one of Liu Weichen's younger sons. After Former Qin collapsed in light of various rebellions after its emperor Fu Jiān's defeat at the Battle of Fei River in 383, Liu Weichen took control of what is now part of Inner Mongolia south of the Yellow River and extreme northern Shaanxi, and while he nominally submitted to both Later Qin and Western Yan as a vassal, he was actually a powerful independent ruler. However, in 391, he sent his son Liu Zhilidi (劉直力鞮 /conf. Chuvash Çăлтăр) to attack Northern Wei's prince Tuoba Gui, and Tuoba Gui not only defeated Liu Zhilidi, but crossed the Yellow River to attack Liu Weichen's capital Yueba (悅拔, in modern Ordos, Inner Mongolia), capturing it and forcing Liu Weichen and Liu Zhilidi to flee. The next day, Liu Weichen was killed by his subordinates, and Liu Zhilidi was captured. Tuoba Gui seized Liu Weichen's territory and people and slaughtered his clan.