Murong Fuyun
Despite this initial alliance between Tang and Tuyuhun, peace did not last even before, and did not last after, Tang's reunification of China, which by 623 was largely complete, as Murong Fuyun, under the advice of his strategist the Prince of Tianzhu, was making several pillaging attacks on Tang every year for the rest of Emperor Gaozu's reign, which ended in 626 as he was forced to abdicate to his son Li Shimin (as Emperor Taizong). The attacks were less frequent thereafter, but were still ongoing.