The Emperor of China was the title of any sovereign of Imperial China reigning between the founding of the Qin dynasty that unified China in 221 BC, until the abdication of Puyi in 1912 following the Xinhai Revolution and the establishment of the Republic of China. The emperor was also referred to as the "Son of Heaven" , a title that predates the Qin unification, and recognized as the ruler of "all under heaven" (i.e., the whole world). In practice not every Emperor held supreme power in China, although this was usually the case.