《隋书·列传·卷二十七》
当时高祖刚刚即位，每念北周诸侯微弱，以致亡国，因此分封诸子为王，让他们的权力与皇室不相上下，以此为磐石之固。皇上让晋王杨广镇守并州，蜀王杨秀镇守益州。
时高祖初即位，每惩周代诸侯微弱，以致灭亡，由是分王诸子，权侔王室，以为磐石之固，遣晋王广镇并州，蜀王秀镇益州。
When Emperor Gaozu had just ascended to the throne, he was always thinking about how the Northern Zhou had been weak and vulnerable, eventually leading to its downfall, so he enfeoffed his children as kings, granting them power comparable to the Imperial Court as a foundation for stability. The Emperor had King of Jin Yang Guang supervise Bingzhou and King of Shu Yang Xiu supervise Yizhou.