The oldest sections of what is now the Grand Canal were completed in the early 5th century BC during the conflicts of China's Spring and Autumn period to provide supplies and transport routes for the states of Wu and Yue.

The network was completed by Emperor Yang of the Sui dynasty in AD 609, linking the fertile Jiangnan region in the south to his capital at Luoyang in the west and to his armies in the far north.

His unsuccessful and unpopular wars and the massive amounts of conscripted labor involved in creating the canal were among the chief factors in the rapid fall of the Sui, but the connection of China's major watersheds and population centers proved enormously beneficial.

[1] Ships in Chinese canals did not have trouble reaching higher elevations after the Song official and engineer Qiao Weiyue invented the pound lock in the 10th century.

[2] The canal has been admired by many visitors throughout its history, including the Japanese monk Ennin (794–864), the Persian historian Rashid al-Din Hamadani (1247–1318), the Korean official Choe Bu (1454–1504), and the Italian missionary Matteo Ricci (1552–1610).

He ordered a canal to be constructed for trading purposes, as well as a means to ship ample supplies north in case his forces should engage the northern states of Song and Lu.

[6] Work began in 486 BC, from south of Yangzhou to north of Huai'an in Jiangsu, and within three years the Han Canal had connected the Yangtze with the Huai River utilizing existing waterways, lakes, and marshes.

The institution of the Grand Canal also obviated the need for army garrisons to become self-sufficient part-time militia-farmers while guarding the dry frontiers between China, Goguryeo and Göktürk.

[1] With the recorded labor of five million people under the supervision of Ma Shumou, the first major section of the Grand Canal was completed in the year 605 and was called the Bian Qu.

[citation needed] However, running alongside and parallel to the course of the canals was an imperial roadway with stables maintained at regular intervals to support a rapid courier system.

[15] One of the greatest benefits of the canal system in the Tang dynasty—and subsequent dynasties—was that it reduced the cost of shipping grain that had been collected in taxes (caoyun)[16] from the Yangtze Delta to northern China.

[19] To ensure smooth travel of grain shipments, Transport Commissioner Liu Yan (in office from 763 to 779) had special river barge ships designed and constructed to fit the depths of each section of the entire canal.

[21] Such an unfortunate event could reduce the legitimacy of a ruling dynasty by causing others to perceive it as having lost the Mandate of Heaven; this was a good reason for dynastic authorities to maintain a smooth and efficient canal system.

[22] During the Song and earlier periods, barge ships occasionally crashed and wrecked along the Shanyang Yundao section of the Grand Canal while passing the double slipways, and more often than not those were then robbed of the tax grain by local bandits.

[24] Much of the Grand Canal was ruined for several years after 1128 when Kaifeng's governor Du Chong (杜充, Dù Chōng, d. 1141) decided to break the dykes and dams holding back the waters of the Yellow River in order to decimate the oncoming Jurchen invaders during the Jin–Song wars.

[29] Chinese engineers built a dam to divert the Wen River to the southwest in order to feed 60% of its water north into the Grand Canal, with the remainder going south.

[34] The Manchus invaded China in the mid-17th century, allowed through the northern passes by the Chinese general Wu Sangui once the Ming capital at Beijing had fallen into the hands of a rebel army.

[35] Because of various factors—the difficulty of crossing the Yellow River, the increased development of an alternative sea route for grain-ships, and the opening of the Tianjin-Pukou Railway and the Beijing-Hankou Railway—the canal languished and for decades the northern and southern parts remained separate.

[citation needed] The Grand Canal played a major role during Mao Zedong's Great Leap Forward as it provided an efficient way to transport grain.

Around Hangzhou, for instance, a $250 million restoration project begun in 2001 improved water quality to the point where it no longer produces a noticeable odor and is once again capable of supporting some fauna.

It rose to a height of 42 meters (138 ft) above the Yangtze, but environmental and technical factors left it with chronic water shortages until it was re-engineered in 1411 by Song Li of the Ming.

Song Li's improvements, recommended by a local man named Bai Ying, included damming the rivers Wen and Guang and drawing lateral canals from them to feed reservoir lakes at the very summit, at a small town called Nanwang.

After leaving Hangzhou heading north toward Beijing, the canal passes around the eastern border of Lake Tai, through the major cities of Jiaxing, Suzhou, Wuxi, and Changzhou before reaching Zhenjiang.

In Tianjin, the canal heads northwest, for a short time following the course of the Yongding, a tributary of the Hai River, before branching off toward Tongzhou on the edge of the municipality of Beijing.

The canal was an important artery of transport and supply for the region during periods of disunity in medieval China and was particularly prosperous and vital during the Southern Song, who established their capital at Lin'an within present-day Hangzhou.

[citation needed] From the Tang to Qing dynasties, the Grand Canal served as the main artery between northern and southern China and was essential for the transport of grain to Beijing.

Since the founding of the People's Republic of China in 1949, the canal has been used primarily to transport vast amounts of bulk goods such as bricks, gravel, sand, diesel, and coal.

[58] In the late 1200s, Marco Polo traveled extensively through China and his trips included time on the Grand Canal, then a major artery for shipping silk, porcelain, and wine.

[citation needed] In 1488, the shipwrecked Korean scholar Choe Bu traveled the entire length of the Grand Canal on his way from Zhejiang to Beijing (and on to Korea) and left a detailed account of his trip.

[60] In 1600, Matteo Ricci traveled to Beijing from Nanjing via the Grand Canal waterway to gain the support of the Wanli Emperor of the Ming dynasty with the help of Wang Zhongde, the Director of the Board of Rites in the central government of China at the time.