In spring 630, Li Jing, employing six separate cavalry formations of nearly 100,000 men along a 1,200 km front, captured the Wuyang Range outside Dingxiang (定襄, in modern Hohhot, Inner Mongolia), approaching Ashina Duobi's court. He then sent spies to Ashina Duobi's camp and persuaded a number of his close associates, including Kangsumi (), to surrender (along with Sui's Empress Xiao and her grandson Yang Zhengdao). Li Jing's nighttime assault on the walls of Dingxiang forced Ashina Duobi to withdraw to Iron Mountain (Tieshan) in the Yin Mountains where he offered to submit to Emperor Taizong—but while he was negotiating with the Emperor Taizong's envoy Tang Jian (), he was also considering withdrawing further north of the Gobi Desert. Li Jing and Li Shiji, believing that Ashina Duobi was merely stalling for time, joined their forces and their vanguard, Su Dingfang, attacked Ashina Duobi's encampment on March 27, 630, defeating him and killing his wife (Sui Dynasty's Princess Yicheng). Ashina Duobi fled further to his subordinate khan Ashina Sunishi (), but was soon captured by the Tang generals Li Daozong and Zhang Baoxiang () and delivered to Chang'an. Turkic nobles largely surrendered to Tang, while the Turkic Khaganate's people scattered in three directions—either surrendering to Tang, surrendering to the Xueyantuo, or fleeing west to the Western Turkic Khaganate and the nearby kingdoms such as Qocho, Kucha, and Tuyuhun.