 Yang Gao was said to be intelligent and handsome in his childhood, as well as filially pious—such that when Emperor Yang was ill and unable to eat, Yang Gao would refuse to eat as well, and when Empress Xiao was ill and considered moxibustion, he volunteered to undertake it first.Emperor Yang, when he was under siege by the Eastern Turk leader Shibi Khan in 615 at the seat of Yanmen Commandery in present-day Daixian, Shanxi, was recorded as so desperate that he was not doing anything except holding Yang Gao and crying.In 618, while Emperor Yang was at Jiangdu (江都, in modern Yangzhou, Jiangsu), forces participating in a coup led by the general Yuwen Huaji entered the palace and surrounded him.