As was the custom, his personal name and the name after assuming the title Qaghan were different. His personal name was recorded in Chinese characters as 阿史那默棘連. His name after assuming the title was Bilgä Qaγan.. His regnal name was Tengri-like and Tengri-born Turk Bilge Kagan according to the Orkhon inscriptions.
Early years
He was born in 683, just in early years of the khaganate. He campaigned alongside his father from early years as a child. He was created as Tardush shad and given command over western wing of empire in 697 by Qapaghan. He managed to annihilate Wei Yuanzhong's army in 701 with his brother. He also reconquered Basmyltribes in 703. He also subdued Yenisei Kyrgyz forces in 709, after their disobedience had to reconquer and kill their Qaghan in 710. He killed Türgesh khagan Suoge at Battle of Bolchu. In later years of Qapaghan, he had to fight four battles in a year starting from 714, resubduing tribes and nearly was killed in an ambush from Uyghur forces in 716.
Reign
In 716, Qapaghan Qaghan, the second Qaghan, was killed in his campaign against the Toquz Oghuz alliance and his severed head was sent to Chang'an. Although his son Inel Khagan succeeded him, Bilgä's brother Kul Tigin and Tonyukuk carried out a coup d'état against Inel Qaghan. They killed him and made him BilgäQaghan. His name literally means "wise king". He appointed his brother Kul Tigin to be Left Wise Prince, which made second most powerful person in realm. He re-subdued Huige in 716. He also appointed his father-in-law Tonyukuk to be Master Strategist. New reforms and stabilization of the regime, caused tribes that fled Tujue to come back. Tang chancellor Wang Jun, believing that the Göktürks who surrendered would try to flee back to the Göktürk state, suggested that they be forcibly moved into the heart of the empire to prevent them from doing so. Before Wang's suggestion could be acted upon, however, there was an uprising by the Göktürks who surrendered, under the leadership of Xiedie Sitai and Axilan. Xue and Wang tried to intercept them and dealt them defeats, but they were able to flee back to the Göktürk state anyway. This defeat led to Xue Ne's retirement.
Religious policy
At some point in his life, he wanted to convert to Buddhism, settle in cities. However, Tonyukuk discouraged him from this, citing Tujue's small numbers and vulnerability to Chinese attack. While Turks' power rested on their mobility, conversion to Buddhism would bring pacifism among population. Therefore, sticking to Tengriism was necessary to survive.
Later reign
In 720, Wang believed that the Pugu and Xiedie tribes of the region were planning to defect to Eastern Tujue and attack with Eastern Tujue troops. He thus held a feast and invited the chieftains, and, at the feast, massacred them. He then attacked the Pugu and Xiedie tribes in the area, nearly wiping them out. He then proposed a plan to attack Qaghan along with the Baximi, Xi, and Khitan. Emperor Xuanzong also recruited Qapaghan Khagan's sons Bilgä Tigin and Mo Tigin, Yenisei Kyrgyz Qaghan Kutluk Bilgä Qaghan and Huoba Guiren to fight against Tujue. Tonyukuk cunningly launched first attack on Baximi in 721 autumn, completely crushing them. Meanwhile, Bilgä raided Gansu, taking much of the livestock. Later that year Khitans, next year Xi were also crushed. In 726, his father-in-law and chancellor Tonyukuk died. In 727, he sent Buyruk Chor as en emissary to Xuanzong to send 30 horses as gift. He also alarmed him of Me Agtsom's proposal of anti-Tang alliance. This alarm proved to be true when Tibetan general We Tadra Khonglo invaded Tang China in 727, sack Guazhou, Changle, Changmenjun and Anxi. On 27 February 731, Kul Tigin died, for which Qaghan mourned and ordered a great funeral ceremony. In 733, he defeated rebellious Khitan tribes.
Death
Just after sending an emissary to Xuanzong to gain heqin alliance, he was poisoned by Buyruk Chor. He did not die immediately and he had time to punish the family of Buyruk Chor with death. He died on 25 November 734, his burial ceremony took place on 22 June 735.
