Bilge Qaghan (Old Turkic: 𐰋𐰃𐰠𐰏𐰀:𐰴𐰍𐰣, Bilgä Qaγan; Chinese: 毗伽可汗, Pinyin: píjiā kěhàn, Wade-Giles: p'i-chia k'o-han); official title: "Tengriteg Tengride bolmuş Türk Bilge Kağan" (the Turkic Bilge Qaghan who has become like a god in heaven), was one of the qaghans of the Second Göktürk Khaganate. He is regarded as one of the most important figures in Turkic history.
He was born in 683 in the vicinity of Mount Çugay-Kuz, then the center of the khaganate. When he was 8 years old, following the death of his father İlteriş Qaghan in 691, he was raised under the protection of his uncle Kapgan Qaghan.
Appointed by his uncle in 697 as shad over the Tardush, Bilge Qaghan was brought up under the supervision of his ataman (an institution functioning similarly to the atabeg of the Seljuks and the lala of the Ottomans), Köli Čor. In 698, at the request of his uncle Kapgan Qaghan, he took part in the Battle of Bolçu against the Türgesh. In 699 he was appointed Shad of the Right Wing by his uncle Kapgan Qaghan and given an army of 20,000 men. In 700, Bilge Qaghan launched a military campaign against the Tanguts. At the end of the battle he captured the children, women, horse herds, and all the property of the Tanguts, whom he had defeated. In 701 he took part in the Battle of Iduk Baş, fought in the Southern Ordos region between the Göktürk army under the command of Kapgan Qaghan and the 50,000-strong Tang army under the command of Ong Tutuk. At the end of the battle the Sogdian colonies passed into Göktürk hands. In 703 he campaigned against the Basmyl, who had ceased paying tribute to the Göktürks, defeated their ruler bearing the title Iduk Kut, and brought them back under submission. On 17 January 707 he took part in the great Battle of Ming Şa, fought between the Göktürk army under the command of Kapgan Qaghan and the Tang army under the command of Çaça Sengün. Bilge Qaghan played an important role in subduing the Chik at Örpen in 709 — who had rebelled against the Göktürk confederation as a result of the Tang dynasty's policy of incitement — the Kyrgyz at Kögmen in 710, and the Türgesh at Bolçu in 711. In 711–712, during the Muslim conquest of Transoxiana, at the request for aid from the Göktürk allies in Transoxiana, he took part in the campaign launched against the Arabs. However, this campaign did not achieve the desired result. In 714, Bilge Qaghan defeated the Karluks — who had rebelled although they had no grievance — in a battle at Tamag Iduk Baş. After this defeat the Karluks took refuge with the Tang dynasty. The years 715–716 were the most intense period of the Göktürks' struggles against the confederation of tribes subject to them. This time the rebels were the Toquz Oghuz, who formed the backbone of the khaganate. Nor were they alone: the Karluks and Basmyl were with them. Together with his brother Kül Tigin, Bilge Qaghan had to fight them four times in a single year. The first battle took place at Togu Balık. Unable to gain the upper hand over one another, the two sides clashed a second time at Andırgu. Still unable to prevail, they fought a third time at the head of the Çuş River. After this battle, again inconclusive, the two sides faced each other at Ezginti Kadız for a decisive outcome. The battle fought here became one of the bloodiest the Turks ever waged among themselves. In the fiercely contested battle, the Göktürks swept away the Oghuz. After 22 July 716, when his uncle Kapgan Qaghan was killed on his return from the Bayırku campaign, the Turkic assembly (Türk Toyu) chose his uncle's son İnel as qaghan. Over the following few months, İnel Qaghan's inability to steady the khaganate on account of his youth and inexperience was interpreted as the divine fortune (kut) having been taken away from İnel. Before long, despite Tonyukuk's opposition, İnel Qaghan was executed in February 717 along with his relatives, supporters, and kin, through a rather bloody coup supported by Alp Eletmiş and planned and carried out by Kül Tigin.