Around the new year 630, with Eastern Tujue in internal turmoil, with its Jiali Khan Ashina Duobi attacking his nephew and subordinate khan, the Tuli Khan Ashina Shibobi (阿史那什鉢苾), Emperor Taizong commissioned Li Jing, Li Shiji, Wei Xiaojie, Li Daozong, Chai Shao (柴紹), and Xue Wanche (薛萬徹) to attack Eastern Tujue, with Li Jing in overall command. Li launched his attack in a surprise manner, from Mayi through Wuyang Range (惡陽嶺, in modern southern Hohhot, Inner Mongolia), capturing the important city of Dingxiang (定襄, in modern Hohhot). In fear, Ashina Duobi retreated to Qikou (磧口, in modern Xilin Gol League, Inner Mongolia). Li Jing then sent secret messengers to persuade his associate to surrender. One of them, Kangsumi (康蘇密), took Emperor Yang's wife Empress Xiao and their grandson Yang Zhengdao (楊政道), whom Eastern Tujue had created the Prince of Sui, and surrendered to Li Jing. Ashina Duobi sent messengers to Emperor Taizong, offering to submit and to pay homage to him later, but was still considering fleeing further with his forces. Emperor Taizong sent the official Tang Jian (唐儉) as an envoy to Ashina Duobi, but also ordered Li Jing to escort Ashina Duobi. Li Jing, reading between the lines and believing that Emperor Taizong's order was to "attack" Ashina Duobi, after joining forces with Li Shiji, launched the attack. They defeated and captured most of Ashina Duobi's remaining forces and killed his wife, Sui's Princess Yicheng. Ashina Duobi fled further, and was soon captured by the generals Li Daozong and Zhang Baoxiang (張寶相). Eastern Tujue's nobles all submitted to Tang. In recognition of Li Jing's great victory, Emperor Taizong issued a general pardon and ordered his people to feast for five days. He also created Li Jing the greater title of Duke of Dai.