Several of these rebel leaders—including Li Yuan, Liu Wuzhou, Liang Shidu, Dou Jiande, and Gao Kaidao—formally submitted to Ashina Duojishi and received Eastern Göktürk military aid, with Ashina Duojishi's strategy apparently to keep China divided. In winter 617, Li Yuan captured Chang'an, declaring Yang You emperor (as Emperor Gong), while honoring Emperor Yang as "Taishang Huang" (retired emperor); these declarations were not recognized by most of Sui territory, which still recognized Emperor Yang as emperor. Li himself became regent with the title of Prince of Tang.