Major changes in political structure, social and economic life define the Sui, Tang and Song dynasties. Each period laid the foundation for the next, with changes and improvements to create a new order. The Sui dynasty ruled from 581 to 618 AD. The emperor built monasteries for Buddhism and Taoism throughout the country and appointed Buddhist monks as his chief advisors. (Duiker and Spielvogel, 2009) The Han examination system based on the Confucian classics was revived. Taxation was reformed and a census was introduced to create fair tax collection. In addition, a grant of land was granted to each taxable man. Once a man reached the age of 60, part of the land was returned to the government, the rest could be passed on to his heirs. (Halsall, 1998) It was also a time of great construction. Under the Sui, the Great Wall was rebuilt and the Grand Canal was built. Connecting the Huang, Huai and Yangtze Rivers, the Grand Canal has had a huge impact on travel, commerce and socialization in China. The Tang dynasty was founded in 618 and lasted until 907. The emperor was supreme and government officials were chosen by examination. A census was held to simplify tax collection and recruit citizens to perform work for the empire. It was a period of great territorial expansion. (Halsall, 1998) The emperor also had a great love for the arts, and the Tang became known as the golden age of literature and art. Block printing was invented and made writing more accessible. (Unknown, 2003) Shipbuilding and firearm development were also perfected during this era. The art was heavily influenced by Buddhism, particularly rock sculpture. One of the major problems that arose was the heavy burden of taxation. Many were unable to meet their heavy tax burden. To escape, many placed themselves under the protection of large tax-exempt landowners, or became bandits. (Halsall, 1998) The Song dynasty is actually divided into two distinct periods: the Northern Song from 960 to 1126 AD and the Southern Song from 1126 to 1279 AD. The west of the country had been conquered by nomadic tribes, forcing the emperor to move the capital to Kaifeng, then later to Hangzhou during the Southern Song period. They also lost control of Tibet. (Duiker and Spielvogel, 2009) As they struggled for control of territory, the Song strove to develop their economy and realize their culture..