China's last empire, the Qing, lasted from 1644 to 1911. It began in violence and war as the Manchus swept down from the north, but invaders became emperors and three generations of one family ruled for 133 years. Among them, Michael Wood argues, was China's greatest emperor - Kangxi. Under the Qing, China doubled in size to include Xinjiang in the far west, as well as Mongolia and Tibet, creating the essential shape of China today.