Wu Zetian was a Chinese sovereign, who ruled officially under the name of her self-proclaimed "Zhou Dynasty", from 690 to 705; however, she had previous imperial positions under both Emperor Taizong of Tang and his son Emperor Gaozong of Tang, of the Tang Dynasty of China. Wu was a concubine of Emperor Taizong; after his death she married his successor and 9th son, Emperor Gaozong, officially becoming Gaozong's furen, in 655, although previously having considerable political power prior to this. Gaozong had a debilitating stroke in 660, after which Wu Zetian ruled as effective sovereign until 705. Typical of historical Chinese imperial governments, the nation was mainly ruled by a formal bureaucratic government, under the (at least nominal) control of a sole sovereign, or huangdi. In this