According to History of Northern Dynasties and Zizhi Tongjian, in 545 Tumen's tribe started to rise and frequently invaded the western frontier of Wei. The chancellor of Western Wei, Yuwen Tai, sent
An Nuopanto (Nanai-Banda, a Sogdian from Bukhara,) as an emissary to the Göktürk chieftain Tumen, in an attempt to establish a commercial relationship. In 546, Tumen paid tribute to the Western Wei state. In that same year, Tumen put down a revolt of the Tiele tribes against the Rouran Khaganate, their overlords. Following this, Tumen felt entitled to request of the Rouran a princess as his wife. The Rouran khagan, Anagui, sent a message refusing this request and adding: "You are my blacksmith slave. How dare you utter these words?" Bumin got angry, killed Anagui's emissary, and severed relations with the Rouran Khaganate. Anagui's "blacksmith" (鍛奴 / 锻奴, Pinyin: duàn nú, Wade–Giles: tuan-nu) insult was recorded in Chinese chronicles. Some sources state that members of the Tujue did serve blacksmiths for the Rouran elite, and that "blacksmith slavery" may refer to a kind of vassalage that prevailed in Rouran society. Nevertheless, after this incident Bumin emerged as the leader of the revolt against Rouran.
In 551, Bumin requested a Western Wei princess in marriage. Yuwen Tai permitted it and sent
Princess Changle of Western Wei to Bumin.In the same year when Emperor Wen of Western Wei died, Bumin sent mission and gave two hundred horses.
The beginning of formal diplomatic relations with China propped up Bumin's authority among the Turks. He eventually united the local Turkic tribes and threw off the yoke of the Rouran domination. In 552 Bumin's army defeated Anagui's forces at the north of Huaihuang and then Anagui committed suicide. With their defeat Bumin proclaimed himself "Illig Qaghan" and made his wife qaghatun. According to the Bilge Qaghan's memorial complex and the Kul Tigin's memorial complex, Bumin and Istemi ruled people by Turkic laws and they developed them.