Li Yuanji
Once Li Jiancheng, Li Yuanji, and Chai arrived at Taiyuan, Li Yuan formally declared his rebellion, but maintained the guise of a Sui loyalist and declared that his intention was simply to install on the throne Emperor Yang's grandson Yang You, the Prince of Dai, who was then at Chang'an, and honor Emperor Yang as "Taishang Huang" (retired emperor). Li Yuan first secured his northern flank by contacting Shibi Khan, offering tribute, and received men and horses in exchange. He put Li Jiancheng and Li Shimin in charge of his army and, leaving Li Yuanji in charge at Taiyuan, advanced south. Meanwhile, the Sui officials at Hedong arrested Li Zhiyun and delivered him to Chang'an, where he was executed.