Canal system in sui dynasty. Taking Luoyang as the center, Tongji canal was dug in the first year of Daye (605) to directly communicate with Huanghuai traffic. And transformed the Hangou and Jiangnan Canal. In three years, Yongji Canal was dug again, leading to Zhuo Jun in the north. Coupled with the Guangtong Canal dug in 584 AD, a number of canal systems were formed. Luoyang was the capital of the Sui Dynasty, so when Emperor Yang Di went to the south of the Yangtze River, he started from Luoyang, and you should ask about Tongji Canal.