Yang Xuangan
It is not known when Yang Hongwu was born—other than that it must have been before or not much later than the death of his father Yang Yue (楊岳) in 613. Yang Yue was a younger brother of the Sui Dynasty chancellor Yang Su the Duke of Yue. During the reign of Emperor Yang of Sui, Yang Yue served as the magistrate of Wannian County (萬年, one of the two counties forming the capital Chang'an). After Yang Su's death in 604, Yang Yue had a poor relationship with Yang Su's son Yang Xuangan, and secretly submitted a petition to Emperor Yang stating that one day Yang Xuangan will surely rebel. When Yang Xuangan did rebel in 613, Yang Yue, as Yang Xuangan's uncle, was arrested at Chang'an. Emperor Yang, who was at the eastern capital Luoyang, sent an imperial messenger to order Yang Yue released, but by the time that the messenger reached Chang'an, the officials in charge of Chang'an had already killed Yang Yue. However, because of this, Yang Yue's sons, including Yang Hongwu and at least one brother, Yang Hongli (楊弘禮), were spared. After the general Emperor Gaozu rebelled against Sui rule in 617 and eventually established Tang Dynasty in 618, Yang Hongwu became an imperial guard commander.