Emperor Wu of Northern Zhou
As a Northern Zhou official, Yang Jian served with apparent distinction during the reigns of Emperor Wu of Northern Zhou and Emperor Xuan of Northern Zhou. When the erratic Emperor Xuan died in 580, Yang, as his father-in-law, seized power as regent. After defeating the general Yuchi Jiong, who resisted him, he seized the throne for himself, establishing the new Sui Dynasty (as its Emperor Wen). He was the first Chinese ruler to rule the entire North China after the Xianbei clans conquered that area from the Liu Song dynasty (not counting the brief reconquest of that region by Emperor Wu of Liang).