When I arrived in Yangdi, in order to strengthen centralization and the northern transportation of southern grain, a canal was dug from Jinghuai section to the south of the Yangtze River, with a total length of more than 2,700 kilometers. In the Yuan Dynasty, most of the capital of the Yuan Dynasty (now Beijing) had to dig canals to transport grain from the south to the north. For this reason, three sections of rivers have been dug successively, and the horizontal canal of the Sui Dynasty with Luoyang as the center has been built into a vertical grand canal with Dadu as the center and Hangzhou as the south. Geographically, the Beijing-Hangzhou Grand Canal is divided into seven sections: from Beijing to Tongzhou District, called Tonghui River, from Shenshan Spring in Baifu Village of Changping County to Jishuitan and Zhongnanhai, from Wenmingmen (now Chongwenmen) to the east, from Yangzha Village of Chaoyang District to Tongzhou Gaolizhuang village (now Zhangjiawan Village) to Luhe (now the old road of North Canal), with a total length of 82 kilometers; Tongzhou District to Tianjin is called the North Canal, which is 186 km long. Tianjin to Linqing is called the South Canal, which is 400 kilometers long. Linqing to Taierzhuang is called Lu Canal, which is about 500 kilometers long. Taierzhuang to Huai 'an is called the Central Canal, with a total length of 186 km. Huai 'an to Guazhou is called Li Canal, which is about180km long. Zhenjiang to Hangzhou is called Jiangnan Canal, which is about 330 kilometers long. Yangzhou and Huai 'an are famous cities of the Li Canal. When Yang Di dug canals in the city, Yangzhou and Huai 'an became the north-south transportation hubs, and made use of water transportation to become one of the most prosperous areas in China.