In antiquity, the river was a major tributary of the
Huai River in central China. Tributaries such as the Fan (反), Sui (睢), Tong (潼) and Yi (沂) swelled its banks as it passed through present-day
Yutai,
Pei,
Xuzhou,
Suqian, and
Siyang counties in Shandong and Jiangsu. Its confluence with the Huai occurred at Sikou (泗口) or Qingkou (清口) at present-day
Huai'an in Jiangsu. From a very early date, the Huai was connected with the
Yellow River through the
Honggou Canal (
t s Hónggōu, "Canal of the Wild Geese"). In 486BC,
King Fuchai of
Wu built the
Hangou Canal (
t s Hángōu), connecting the Huai and Honggou to the
Yangtze River to their south. Amid his ongoing wars against
Qi and
Jin, in 483 and 482BC, he further expanded this network with the
Heshui Canal (
t s Héshuǐ Yùnhé), connecting the Si with the
Ji River, engulfing the lower reaches of the Si River below Xuzhou City and those of the Huai River below Huai'an. As a result, the Si River no longer exists in Jiangsu Province. During the
1851–1855 Yellow River floods, the Yellow River once more altered its course northwards, assuming the course of the former
Ji River and again passing north of the Shandong Peninsula in 1852. However, due to the large amount of
silt carried by the river, it left behind a high layer of mud in the lower reaches of the Si River's former course. ==Legacy==