The population density of residential areas south of the Yangtze River, whether in rural areas or cities, is higher than that in the north. Due to the superior climate, soil, natural resources and other natural environment and the particularity of geographical location, this area has enjoyed the reputation of "Land of Abundance" since ancient times, and gradually occupied a pivotal position in the economic structure of China. Especially after the opening of the North-South Grand Canal in Sui Dynasty, this area is at the intersection of the Yangtze River and the Grand Canal, connecting the vast hinterland of western and northern China. Silk produced in Suzhou and Hangzhou has been famous all over the world since the Han Dynasty. Yangzhou, an ancient city with a history of more than 2,400 years, has developed into an important commercial port for opening to the outside world in the Tang Dynasty as a cargo terminal at the southern end of the Canal. During the Ming and Qing Dynasties, it became a commercial center and an important shipping port in the south of the Yangtze River, thus becoming a place where wealthy businessmen gathered. By the Ming and Qing Dynasties, Jiangnan was already the most prosperous area of agriculture, handicrafts and commerce in China.