Planting and processing of the four major Huai medicines The four major Huai medicines specifically refer to the four Chinese medicinal materials of yam, rehmannia, cyperus and chrysanthemum produced in the jurisdiction of Jiaozuo City (ancient Huaiqing Prefecture). They are called "Huai yam", "Huai rehmannia", "Huai cyperus" and "Huai chrysanthemum" in Chinese medicine classics. The production and sales of Huai medicines had already formed a scale as early as the end of the Ming Dynasty. The Huaiqing Prefecture Medicinal Materials Conference was one of the five major medicinal materials conferences in my country at that time. During the reign of Emperor Kangxi of the Qing Dynasty, Huaiqing drug dealers formed a large "Huai Gang" team, and successively built Huai Gang Guild Halls and opened medicine shops in Wuhan, Beijing, Tianjin, Xi'an, Anguo and other places. Huai medicine products are sold to Southeast Asia and European and American countries through ports such as Guangdong, Hong Kong, Shanghai and Tianjin. Countries such as the United States and Japan call them "Hua medicines".