 After the death of Emperor Wu's son and successor Emperor Xuan in 580, Emperor Xuan's father-in-law Yang Jian became regent over his son Emperor Jing of Northern Zhou.Several imperial princes of the Yuwen clan believed that Yang had designs on the throne but failed in a plot to kill him.After the plot, he began executing the imperial princes in earnest, and around the new year 581, he executed Yuwen Da and Yuwen Da's sons.