The Tang Dynasty (June 18, 618 June 1, 907) was an imperial dynasty of China preceded by the Sui Dynasty and followed by the Five Dynasties and Ten Kingdoms Period. It was founded by the Li family, who seized power during the decline and collapse of the Sui Empire. The dynasty was interrupted briefly by the Second Zhou Dynasty (October 8, 690 March 3, 705) when Empress Wu Zetian seized the throne, becoming the first and only Chinese empress regnant, ruling in her own right. The Tang Dynasty, with its capital at Chang'an (present-day Xi'an), which at the time was the most populous city in the world, is generally regarded as a high point in Chinese civilization-equal to, or surpassing that of, the earlier Han Dynasty-a golden age of cosmopolitan culture. Its territory, acquired through the military campaigns of its early rulers, rivalled that of the Han Dynasty. In two censuses of the 7th and 8th centuries, the Tang records estimated the population by number of registered households at a