Tang dynasty  The Tang dynasty (; ) or the Tang Empire was an imperial dynasty of China that ruled from 618 to 907, with an interregnum between 690 and 705. It was preceded by the Sui dynasty and followed by the Five Dynasties and Ten Kingdoms period in Chinese history. Historians generally regard the Tang as a high point in Chinese civilization, and a golden age of cosmopolitan culture. Tang territory, acquired through the military campaigns of its early rulers, rivaled that of the Han dynasty. The Tang capital at Chang'an (present-day Xi'an) was the most populous city in the world in its day. The Lǐ family () founded the dynasty, seizing power during the decline and collapse of the Sui Empire. The dynasty was interrupted for 15 years when Empress Wu Zetian seized the throne, proclaiming the Wu Zhou dynasty and becoming the only legitimate Chinese empress regnant. In two censuses of the 7th and 8th centuries, the Tang records estimated the population by number of registered households at about 50 million people. Yet, even when the central government was breaking down and unable to compile an accurate census of the population in the 9th century, it is estimated that the population had grown by then to about 80 million people. With its large population base, the dynasty was able to raise professional and conscripted armies of hundreds of thousands of troops to contend with nomadic powers in dominating Inner Asia and the lucrative trade-routes along the Silk Road. Various kingdoms and states paid tribute to the Tang court, while the Tang also conquered or subdued several regions which it indirectly controlled through a protectorate system. Besides political hegemony, the Tang also exerted a powerful cultural influence over neighboring East Asian states such as those in Japan and Korea. The Tang dynasty was largely a period of progress and stability in the first half of the dynasty's rule, until the devastating An Lushan Rebellion (755–763) and the decline of central authority in the later half of the dynasty. Like the previous Sui dynasty, the Tang dynasty maintained a civil-service system by recruiting scholar-officials through standardized examinations and recommendations to office. The rise of regional military governors known as "jiedushi" during the 9th century undermined this civil order. Chinese culture flourished and further matured during the Tang era; it is traditionally considered the greatest age for Chinese poetry. Two of China's most famous poets, Li Bai and Du Fu, belonged to this age, as did many famous painters such as Han Gan, Zhang Xuan, and Zhou Fang.