 Emperor Gaozong (reigned 649–683) of the Tang dynasty (618–907) commissioned the scholarly compilation of a "materia medica" in 657 that documented 833 medicinal substances taken from stones, minerals, metals, plants, herbs, animals, vegetables, fruits, and cereal crops.In his "Bencao Tujing" ('Illustrated Pharmacopoeia'), the scholar-official Su Song (1020–1101) not only systematically categorized herbs and minerals according to their pharmaceutical uses, but he also took an interest in zoology.For example, Su made systematic descriptions of animal species and the environmental regions they could be found, such as the freshwater crab "Eriocher sinensis" found in the Huai River running through Anhui, in waterways near the capital city, as well as reservoirs and marshes of Hebei.