It is thought the dynasty originated from the Tuoba clan of the Xianbei tribe. The Tuoba renamed themselves the Yuan as a part of systematic Sinicization. Towards the end of the dynasty there was significant internal dissension resulting in a split into Eastern Wei Dynasty and Western Wei Dynasty. The Jin Dynasty had developed an alliance with the Tuoba against the Xiongnu state Han Zhao. In 315 the Tuoba chief was granted the title of the Prince of Dai. After the death of its founding prince, Tuoba Yilu, however, the Dai state stagnated and largely remained a partial ally and a partial tributary state to Later Zhao and Former Yan, finally falling to Former Qin in 376.

After Former Qin's emperor Fu Jia-n was defeated by Jin forces at the Battle of Fei River in his failed bid to unify China, the Former Qin state began to break apart. By 386, Tuoba Gui, the son (or grandson) of Tuoba Shiyijian (the last Prince of Dai), reasserted Tuoba independence initially as the Prince of Dai. Later he changed his title to the Prince of Wei, and his state was therefore known as Northern Wei. In 391, Tuoba Gui defeated the Rouran tribes and killed their chief, Heduohan, forcing the Rouran to flee west.