In the late Spring and Autumn Period (722-481 BC), Fuchai, the Duke of Wu (present-day Suzhou), ventured north to conquer the neighbouring state of Qi. He ordered a canal be constructed for trading purposes, as well as a means to ship ample supplies north lest his forces should engage the northern states of Song and Lu. This canal became known as the Han Gou, or 'Han-country Conduit'. Work began in 486 BC south of Yangzhou in Jiangsu, and within three years the Han Gou had connected the Yangtze River to the Huai River by means of existing waterways, lakes and marshes.
The Han Gou is actually known as the second oldest section of the later Grand Canal, since the Hong Gou ('Canal of the Flying Geese', or 'Far-Flung Canal') most likely preceded it. It linked the Yellow River near Kaifeng to the Si and Bian rivers, and became the model for the shape of the Grand Canal in the north. The exact date of the Hong Gou's construction is uncertain; its first known written mention was made by the diplomat Su Qin in 330 BC when discussing state boundaries. The historian Sima Qian (145¨C90 BC) dated it much earlier than the 4th century BC, attributing it to the work of the mythological Yu the Great; modern scholars now consider it to belong to the 6th century BC.
This Han Gou section of the canal was not only important for private trade, but also remained continually important for conducting martial marine campaigns. For example, in the year 280 the naval commander Wang Jun led a victorious campaign against Eastern Wu by facilitating the use of this canal for his passing fleet. By the middle of the sixth century AD, its winding course had been rationalised into a straighter canal, the Shanyang River.