李建成
Late in 622, when Liu Heita returned east after receiving aid from the Eastern Turks, defeating and killing Li Shimin's cousin Li Daoxuan (), the Prince of Huaiyang, he again regained most of former Xia territory. Li Jiancheng's staff members Wang Gui and Wei Zheng suggested that Li Jiancheng needed to enhance his own reputation in battle, and so Li Jiancheng volunteered for the mission. Emperor Gaozu thus sent Li Jiancheng, assisted by Li Yuanji, to attack Liu. Li Jiancheng defeated Liu around the new year of 623, and Liu was subsequently betrayed by his own official Zhuge Dewei () and delivered to Li Jiancheng. Li Jiancheng executed Liu in his former capital and returned to Chang'an in triumph. China was, by this point, roughly united under Tang rule.