Daoyuan Li (circa 470–527), also known as Shanzhang, was a native of Fanyang in Tian County. He was a geographer in Northern Wei Dynasty. While working as an official, he inspected many rivers, including the Yellow River and Huai River. He paid special attention to channels and investigated waterways and various geographical features. Based on the ancient writing ‘Water Classic’, which was written during the period of the Three Kingdoms, he adopted a novel style in writing the geographical monograph ‘Commentary on the Water Classic’ (Shuijingzhu). The book documented 1,252 rivers of various sizes with 20 times more annotations than ‘Water Classic’. It consisted of 40 volumes of 300,000 characters fully recording the features, geographical conditions, establishments, developments and related historical events of mountains, forests, wetlands, cities, passes and ports along the rivers. It was the most systematic and comprehensive geographical work in China before the sixth century.