<P> The Han Gou is known as the second oldest section of the later Grand Canal since the Hong Gou (t 鴻溝, s 鸿沟, Hónggōu, "Canal of the Wild 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; it is first mentioned by the diplomat Su Qin in 330 BC when discussing state boundaries . The historian Sima Qian (145--90 BC) knew of no historical date for it, placing his discussion of it just after the legendary works of Yu the Great; modern scholars now consider it to belong to the 6th century BC . </P> <P> The sections of the Grand Canal today in Zhejiang and southern Jiangsu provinces were in large part a creation of the Sui dynasty (581 - 618), a result of the migration of China's core economic and agricultural region away from the Yellow River valley in the north and toward the southern provinces . Its main role throughout its history was the transport of grain to the capital . The institution of the Grand Canal by the Qin dynasty and the Sui dynasty, mostly the Sui, also obviated the need for the army to become self - sufficient farmers while posted at the northern frontier, as food supplies could now easily be shipped from south to north over the pass . </P> <P> By the year 600, there were major build ups of silt on the bottom of the Hong Gou canal, obstructing river barges whose drafts were too deep for its waters . The chief engineer of the Sui dynasty, Yuwen Kai, advised the dredging of a new canal that would run parallel to the existing canal, diverging from it at Chenliu (Yanzhou). The new canal was to pass not Xuzhou but Suzhou, to avoid connecting with the Si River, and instead make a direct connection with the Huai River just west of Lake Hongze . With the recorded labor of five million men and women under the supervision of Ma Shumou, the first major section of the Grand Canal was completed in the year 605--called the Bian Qu . The Grand Canal was fully completed under the second Sui emperor, from the years 604 to 609, first by linking Luoyang to the Yangzhou (and the Yangzi valley), then expanding it to Hangzhou (south), and to Beijing (north). This allowed the southern area to provide grain to the northern province, particularly to troops stationed there . Running alongside and parallel to the canal was an imperial roadway and post offices supporting a courier system . The government also planted an enormous line of trees . The history of the canal's construction is handed down in the book Kaiheji (' Record of the Opening of the Canal'). </P> <P> The earlier dyke - building project in 587 along the Yellow River--overseen by engineer Liang Rui--established canal lock gates to regulate water levels for the canal . Double slipways were installed to haul boats over when the difference in water levels were too great for the flash lock to operate . </P>

Who ordered the construction of the grand canal