One of the cornerstones of traditional Chinese medicine (TCM), herbal medicine has evolved over centuries of clinical practice and empirical results into a vast body of knowledge encompassing more than 6,000 substances, most of whose effects and uses have been documented and researched. The literature on Chinese medicinal herbs is unparalleled and unsurpassed in the world’s medical knowledge; the earliest known pharmacological work was composed before the end of the third century B.C. The first classical Chinese materia medica appeared during the late Han dynasty (25-22- A.D.) and included 365 entries of botanical, zoological, and mineral substances, listing their properties and effects. Subsequent materia medica were assembled during virtually every dynasty from the Liang (456-536 A.D.) to the Qing (1645-1911). Among the major treatments published during these centuries was the 30-volume Materia Medica Arranged According to Pattern, which had 1558 entries, more than 3,000 formulae, and became the official pharmacopoeia of herbal medicine in China for 500 years.