Yang Liang
It is not known exactly when Yang Xiu was born, but it is known that he was the fourth of the five sons of Yang Jian and Yang Jian's wife Dugu Qieluo. As the third of his older brothers, Yang Jun, was born in 571 (his younger brother, Yang Liang, similarly has an unknown birth year) and he was already born at least by the time that Yang Jian seized the throne from Emperor Jing of Northern Zhou, ending Northern Zhou and establishing Sui Dynasty as its Emperor Wen in 581, he would have been born sometime between 572 and 579. In 581, after Emperor Wen took the throne, he appointed both of his sons as imperial princes, and Yang Xiu was appointed the Prince of Yue.