Empress Wu, commonly known as Wu Zetian, personal name Wu Zhao, was the only undisputed female sovereign in the history of China. She had previously held power as the empress consort of Emperor Gaozong of the Tang dynasty from 660 to 683 and as empress dowager during the reigns of her sons, Emperors Zhongzong and Ruizong, between 683 and 690. She was the sole ruler of the self-styled Zhou dynasty from 690 to 705.