Shuijingzhu 水经注 Commentary to the River Classic
The Shuijing 水经 "The river classic" was an ancient Chinese geographical book describing the course of rivers. It had been transmitted as a core component together with its commentary, the Shuijingzhu 水经注 "Commentary to the river classic". The classic had been written by Sang Qin 桑钦 during the Three Kingdoms period 三国 (220-280), the commentary by Li Daoyuan 郦道元 during the Northern Wei period 北魏 (386-534). The original text contained 40 juan "scrolls" of which 5 were lost. Later some chapters were divided in order to regain the original number.
For his commentary, Li Daoyuan did not only have the necessary geographical experience from his profession when he was inspecting canals, dykes and rivers, but he also studied a lot of old and contemporary books on geography. The original Shuijing only dealt with 137 rivers, and Li Daoyuan added so much information about other rivers that the Shuijingzhu can not dealt with as a commentary but is in fact a book of its own. It is twenty times as large as the old Shuijing and discusses the geographical course and the cultural background of 1,252 rivers and creeks. The importance of the Shuijingzhu lies in its character as a vast treasury for all types of information on the local economy, society, and geography, not only during the Northern Dynasties period but through the ages. The rivers are described from their source, with the tributaries, river forks and so on down to their estuary mouth. All this is very important information for the reconstruction of the early Chinese hydrological environment. Li Daoyuan, collecting written sources and writing from his own experience, is very cautious towards his sources. This makes his book even more valuable. One exception is that he was not able to deal with rivers of southern China with the same diligence as that of the north because China was divided at that time into the Southern and Northern dynasties.
During the ages, many errors have crept in, mainly in places where the old Shuijing was confused with Li Daoyuan's part. The Qing period 清 (1644-1911) scholars Quan Zuwang 全祖望, Zhao Yiqing 赵一清 and Dai Zhen 戴震 tried to amend those errors. In the late 19th century Yang Shoujing 杨守敬 collected those commentaries in his publication called Shuijingzhu shu 水经注疏.