Li used his position as an official with business in different places to carry field investigations. He is known to have visited the area belonging to the present-day Henan, Shandong, Shanxi, and Jiangsu provinces.[2][3]
Another source for his knowledge was the study of ancient geographical books he had access to, like the Classic of Mountains and Seas (Shanhaijing) completed by the time of the early Western Han dynasty) and the Water Classic (Shuijing), written by Sang Qin during the Three Kingdoms period and later commentated on by Jin dynasty writer Guo Pu. Li vastly expanded the Water Classic, doing his own research and fieldwork. The original Water Classic has not survived but covered 127 rivers and streams and contained about 10,000 characters;[2] Li's Commentary on the Water Classic discusses 1252 watercourses and contains about 300,000 characters in total.[3] The book maps and describes the rivers and streams along with the history, geography and culture of the surrounding region.
