Emperor Taizong's campaign against Tuyuhun

Emperor Taizong of Tang (r. 626-649), the second emperor of Tang China faced challenges throughout his reign from Tang's western neighbor, the state of Tuyuhun, whose Busabuo Khan Murong Fuyun constantly challenged Chinese authority in the border regions. In 634, Emperor Taizong launched a major attack, commanded by the major general Li Jing, against Tuyuhun, dealing Tuyuhun forces heavy defeats and causing Murong Fuyun's subordinates to assassinate him in 635. Tuyuhun, thus weakened, no longer remained a major power in the region, and while Tang, ironically, played the role of protector for Murong Fuyun's son, the Gandou Khan Murong Shun, and grandson, the Ledou Khan Murong Nuohebo, Tuyuhun was never able to recover, particularly with its southwestern neighbor, the Tibetan Empire, constantly attacking it. By 672, during the reign of Emperor Taizong's son Emperor Gaozong of Tang, Tang was forced to move Tuyuhun remnants into its own territory, ending Tuyuhun.

Throughout the reign of Emperor Taizong's father Emperor Gaozu, there were repeated cycles of Tuyuhun, then ruled by the Busabo Khan Murong Fuyun, making incursions into the modern Sichuan and southern Gansu regions and offers of peace by both sides, never longstanding. These incursions continued after Emperor Taizong became emperor in 626—although they appeared to decrease in frequency, as the only incursions recorded in the Chinese chronicle Zizhi Tongjian were in 628, when Tuyuhun forces attacked Min Prefecture (岷州, roughly modern Dingxi, Gansu), and 632, when Tuyuhun forces attacked Lan Prefecture (蘭州, roughly modern Lanzhou, Gansu). It was said that, with regard to Tuyuhun's generally hostile attitude toward Tang, that Murong Fuyun had, in his old age (although it is not known what his age was at this point), taken the posture at the advice of his strategist, the Prince of Tianzhu.

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