In 542 he put down a revolt of the Tiele tribes against their overlords the Avars (Rouran, Ruan-Ruan). In return he asked and was refused the hand of an Avar princess. His next move was to successfully establish contact with the Wei state in China. According to Chinese records, in 545 the Sogdian envoy An Nopantuo led a diplomatic mission to China. As a result of the mission, the Göktürk-Chinese alliance was sealed by Bumin's marriage to the princess Wei Chang'le (長樂公主).
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 Avar domination. With their defeat he proclaimed the Turkic Empire (Gökturk Khaganate) and assumed the title of Il-Khagan ("great-king", 伊利可汗) at the sacred Mt. Ötüuken.
Bumin died within several months after proclaiming himself Il-Khagan. He was succeeded by his brother Istami in the west and by his son Muhan Khan in the east. In less than one century, his empire expanded to comprise most of Central Asia.