The Longest Canal in the Ancient World-Sequel І
The throne of the Eastern Jin Dynasty ended up in the hands of the usurper Liu Yu, who proclaimed himself emperor of the Song Dynasty. In the following one and a half centuries or so, sovereignty passed frequently from one dynasty to another, both in the south, from the Song to the Qi, then to the Liang, and the Chen; in the north from the Northern Wei to the Eastern Wei, then the Western Wei, the Northern Qi, to the Northern Zhou. In 581 Yang Jian took the throne from the Northern Zhou Dynasty and crowned himself as Emperor Wen Di of the Sui Dynasty. The capital was set in Chang'an. In 589 the Sui Dynasty conquered the Chen, putting China under one single sovereign again after 270 years of division.
The war-torn economy began to recover and prosper now that the "walls" between the south and the north were knocked down. People of different nationalities were able to interact and intermingle in a more peaceful way.
Yang Jian died in 604, passing the throne to his son Yang Guang, who was to be known as Emperor Yang Di (560-618). His empire was now economically stable enough for large architectural projects, and he wasted no time in starting them.
Emperor Yang Di first had a 2,000-kilometer-long ditch dug out from Longmen to Shangluo, forming a curved defense line for Chang'an the capital and Luoyang the eastern capital.
In the spring of 605, work on a new Luoyang, 9 kilometers west of the old city, began, together with the building of new palaces and royal gardens.
The most ambitious undertaking Emperor Yang Di launched was a great canal that ran some 2,400 kilometers from Zhuojun in the north, through Luoyang the eastern capital, to Yuhang in the south. Millions of laborers worked day and night for six years until this audacious architectural feat, equaling the Great Wall in its impressiveness, was completed.
The practicality of the canal was great. Instead of freight by road, food produced from southern China could be transported swiftly and on a large scale by canal - the only watercourse running north and south navigable by large cargo boats - to the north, the political and cultural center of the empire, where there was an imperative demand for food.
But, as such a colossal and costly project, the canal also became a heavy political liability.