The Caoyun System (simplified Chinese: 漕运系统; traditional Chinese: 漕運系統; pinyin: Cáoyùn Xìtŏng) was a water and land based grain transportation system begun in China during the Qin dynasty (221 BCE – 206 BCE) which saw continual use until the Qing dynasty (1644–1911). The primary purpose of the caoyun was tax collection, since grain was a major payment method accepted by the imperial administration. The system also played a secondary role as a distribution network for army provisions whilst management of shipbuilding and tariffs also fell within its ambit.
In 647 BCE, the State of Jin suffered major crop failure. Duke Mu of Qin despatched a large fleet of ships manned by Corvée labour from his capital at Yong (雍) in modern-day Fengxiang County, Shaanxi Province. The ships carried several thousands of tons of cereal and proceeded along the Wei, Yellow and Fen Rivers before arriving at the Jin capital Jiang (绛) (south east of modern-day Yicheng County, Shanxi Province). Later, in 486 BCE, King Fuchai of Wu linked the Yangtze and Huai Rivers by excavating the Han Ravine (邗沟) so that water flowed from the Yangtze through the Lakes Fanliang (樊梁湖), Bozhi (博芝湖) and Sheyang (射阳湖) into the Wei at Huai'an. This waterway was subsequently used to transport provisions for the army. Three years afterwards King Fuchai further extended the Han Ravine via the Heshui Canal (荷水运河) to connect with the Si River in Shandong Province.
In 214 BCE the first Chinese Emperor Qin Shi Huang ordered construction of a canal connecting the Xiang River and the Lijiang in order to supply his troops for an attack on the Xiongnu nomads. Designed by Shi Lu (史祿), the resulting Lingqu Canal is the oldest contour canal in the world. This canal along with the Zhengguo Canal in Shaanxi Province and the Dujiangyan Irrigation System in Sichuan Province are known as “The three great hydraulic engineering projects of the Qin dynasty”.
During the Chu–Han contention (206–202 BCE), General Xiao He used the Wei River to transport provisions for his army, thereby creating an effective logistics supply network. In 129 BCE, the sixth year of Emperor Han Wudi, a canal was cut through the northern foothills of the Qin Mountains running parallel to the Wei River linking Tongguan with Chang’an and greatly reducing the amount of time needed to transport goods between the two cities.
Although the Sui dynasty lasted only 37 years from 581 until 618, its rulers made a major contribution to improving the caoyun system. The Hai, Yellow, Huai, Yangtze and Qiantang Rivers were all interlinked through the construction of canals thus laying the groundwork for further development during later dynasties. These were the Guangtong Canal (廣通渠), Tongji Canal (通濟渠), Shanyang Channel (山陽瀆) and Yongji Canal (永濟渠) which formed the basis of a large scale canal based transport network.
At the time of Emperor Jingzong of Tang (r. 824–827) the canal system had become too shallow. This restricted the movement of salt and iron which were important government monopolies so to solve the problem seven rivers were diverted to the east.
During the Song dynasty the capital Daliang (大梁), modern day Kaifeng, used the Bian Yellow, Huimin (惠民河) and Guangji (广济河) Rivers as part of the Cáoyùn network. In 976 CE during the reign of Emperor Taizong of Song more than 55 million bushels of grain were moved along the Bian River to the capital. By the time of Emperor Renzong of Song (r. 1022–763) the amount had increased to 80 million bushels.
The Yuan Dynasty saw the establishment of a government body in the form of a "Si" (司) near the capital to oversee the Caoyun System. Known as the Huai & Yangtze Rivers Grain Transport Office, (江淮都漕运司) this was an offshoot of the Three Departments and Six Ministries of the administrative third grade or "San Pin" (三品). This office was responsible for arranging grain transportation to the Luan River (滦河) then onwards to the capital at Dadu (modern day Beijing) using more than 3,000 boats. Sea based transportation within the Cáoyùn system was also important with canals playing a subsidiary role.
In 1368, the first year of the reign of the Ming Hongwu Emperor, the Capital Grain Transport Office (京畿都漕运司) was established under the auspices of a fourth grade (四品) commissioner. At the same time, a Cáoyùn governor-general’s office was set up in the prefectural capital of Huai'an, Jiangsu Province. Its responsibilities were to manage the Cáoyùn network and ensure that annual grain shipments remained at around 40 million tons. Boatyards were also established in Anqing, Suzhou, Hangzhou, Jiujiang, Zhangshu and Raozhou (饶州) (modern day Poyang County). At Huai'an, a boatyard 15 kilometres (9.3 mi) northwest of the Yangtze River ran for a distance of 23 Chinese miles (c. 11.5 kilometres (7.1 mi). Overall responsibility for all these locations lay with a department of the Ministry of Works. Every year, regulations fixed the total amount of tax payable by the entire country in grain via the Cáoyùn system at 29.5 million bushels. Of this, 12 million bushels were allocated to local governments, 8 million bushels supported the army on the northern border, 1.2 million bushels went to the capital in Nanjing whilst 8.2 million bushels were used to supply Beijing.
From 1415 onwards, imperial regulations stated that the Cáoyùn system should use only the country’s canal network thereafter all seaborne transportation stopped. This situation remained virtually unchanged until the beginning of the 19th century and as a result, during both the Ming and Qing Dynasties, the volume of Cáoyùn grain transported via the Grand Canal far exceeded that of the preceding Yuan Dynasty.
During the Ming dynasty the usage pattern of the Caoyun system went through three successive phases. At first the "zhiyun" (支运) variant evolved as grain tax transportation switched from the sea to the country’s canal and river network. At Huai’an, Xuzhou, Linqing and other locations, warehouses were established to store taxes paid in grain and delivered by the local population. This was then shipped north to provision the army once every quarter. Storage became unnecessary with the advent of the "duiyun" (兑运) form where taxes paid by the common people were partly used to directly pay the transportation fees for army supplies on the journey north. During the third stage known as "changyun" (长运) or "gaidui" (改兌), the army took responsibility for the movement of grain from south of the Yangtze River.
According to Ming dynasty scholar Qiu Jun (邱濬): “Use of the river and canal network saved 30–40% of costs compared to road transportation whereas the savings achieved using sea-borne transport were 70%–80%.”
Although the Qing dynasty continued to use the existing Caoyun System it had numerous disadvantages and caused the government many headaches. In 1825 during the reign of the Daoguang Emperor a maritime shipping office was established in Shanghai with a grain tax receiving station at Tianjin. Qishan and other senior ministers thereafter managed the first grain shipments by sea. Operations in Tianjin quickly grew to outstrip those based in Linqing, Shandong Province. Before the First Opium War of 1839–42 and the Second Opium War (1856–60), yearly caoyun maritime shipments reached around 4 million bushels of grain per annum.
A series of events towards the end of the Qing dynasty led to the ultimate decline of the Caoyun System:On the 21 July 1842, during the later stages of the First Opium War, British troops attacked and occupied Zhenjiang near the confluence of the Grand Canal and Yangtze River, effectively blocking operation of the Caoyun System. As a result, the Qing Daoguang Emperor decided to sue for peace and agreed to sign the Treaty of Nanking which brought hostilities to an end.
The Taiping Rebellion of 1850–64 resulted in the loss of Nanjing and the Anhui segment of the Yangtze River for ten years from 1853 onwards thereby curtailing the Cáoyùn network. During the war with the rebels, major canal side towns including Yangzhou, Qingjiangpu (清江浦), Linqing, Suzhou and Hangzhou suffered serious damage or were razed to the ground.
After the yellow river changed course in 1855, the Cáoyùn canals in the Shandong region gradually silted up. Thereafter, the principle routes for grain shipment were maritime.
In 1872, an office to promote investment in steamships was established in Shanghai when steamships became the official vessels used within the Cáoyùn system.
All canal based traffic of Cáoyùn grain ceased in 1901.
The post of Cáoyùn governor-general was abolished in 1904
1911 saw the opening of the Jinpu railway linking Tianjin and Zhenjiang such that the importance of the Grand Canal and the towns along its banks significantly dropped.