In fall 617, Xue Ju claimed the title of Emperor of Qin. He created his wife Lady Ju empress, and he created Xue Rengao crown prince. Xue Rengao subsequently captured Tianshui, and Xue Ju moved his capital to Tianshui. As Xue Rengao was fierce but often overly cruel to those he captured, Xue Ju often warned him, "You are capable of great things, but you are strict and cruel, with no grace to others. One day you will surely destroy the state I established and our clan." According to traditional historical accounts, however, Xue Ju himself was also cruel, often killing soldiers he captured, and also often cut off their tongues and noses, and therefore did not gain as much following as he hoped. When he sent Xue Renyue south to try to capture lands in modern Sichuan, Xue Renyue was blocked by Xiao Yu the governor of Hechi Commandery (河池, in modern Baoji, Shaanxi) and unable to advance. He also sent his general Chang Zhongxing () west of the Yellow River to attack Li Gui, who had by then seized the territory west of the Yellow River. Chang, however, was defeated by Li Gui's general Li Yun (), and the entire army was captured by Li Gui, although Li Gui released them back to Xue Ju.