The Northern Zhou Dynasty, strategically based in the basin of the Wei River, is supreme in Northern China.

In the south, only the Chen Dynasty remains a rival.

Emperor Xuan, intending to conquer the Chen Dynasty in summer 580, sends Yang Jian to be the commandant at Yang Province (roughly modern Lu'an, Anhui) to prepare for the campaign.

Before Yang Jian can depart, however, Emperor Xuan suddenly grows seriously ill. Two of Emperor Xuan's close associates, Liu Fang and Zheng Yi, who are friends of Yang's, summon Yang to the palace to prepare to serve as regent, overriding the desire of another close associate, Yan Zhiyi, to appoint as regent Emperor Xuan's uncle Yuwen Zhao, the Prince of Zhao.

Emperor Xuan soon dies, and Zheng and Liu issue an edict in Emperor Xuan's name appointing Yang regent.