Yam, also known as yam, native to northern China, the main producing areas of Henan, currently in Henan, Hebei, Shandong, Shanxi and southern Guangxi, Fujian, Guangdong, Taiwan are widely planted, Japan and South Korea also planted. As one of the most important tonic materials of traditional Chinese medicine, there is no side effect, so it has been evaluated by the physician as "warm" and "sex". It is a model of "food and medicine homologous", which can be used as normal food. Avoid, suitable for any crowd, any physical, including the elderly, children, pregnant women and other special groups.

　　Jiaozuo, summer called "Qin Huai", later known as "Huaizhou", yuan called "Huai Meng Road", the Ming and Qing Dynasties as "Huaiqing House." Here the climate and environment were experts summarized as "spring is not drought, summer is not too hot, autumn, but waterlogging, winter, but cold", especially for the growth of yam. Because of this north by the Taihang Mountains, south of the Yellow River, was the mountains and rivers embrace, named "pregnant", also known as "three hundred years Huaichuan." Here the formation of the soil to the Yellow River alluvial, and absorb the Taihang Mountains karst landforms by the rain erosion and infiltration of the composition, forming a loose fertile, distinctive yellow land, especially for yam, yellow, Achyranthes and other rhizome The growth of the material. Unique days, geography, is the yam medicine can crown the world the basic conditions.

　　The so-called "orange Health Huainan was orange, was born in Huaibei was trifoliate orange" ancient doctors such as Sun Simiao, Zhang Zhongjing, Li Shizhen and other drugs will be divided into sub-drug-producing areas. As ejiao to Shandong East A, ginseng to Changbai Mountain as authentic, yam recognized by the Huaiqing government in Henan Province can only be used as medicine. "Shen Nong's Herbal Classic", "map by the Materia Medica" and "Compendium of Materia Medica" are specifically marked by the yam, origin for the "pregnant." "Materia Medica Quan" mentioned when the yam said, "North and South states and county production, but Huaiqing who good." "Shen Nong's Materia Medica" Another plaintext, "yam all over the production, to Huaiqing in Henan real estate good." Chinese medicine, the most widely circulated, the most influential prescription is Liu Wei Di Huang Wan, known as the first party (into the party no later than the Han Dynasty). Old Chinese medicine are aware of authentic Liu Wei Di Huang Wan the most important ingredients, namely yam and yellow, should be produced by Huaiqing House. Literary moniction "Dream of Red Mansions" to all-encompassing, the details of the amazing, the book written in the tenth back, Zhang Taiji for Qin Keqing diagnosis and treatment, out of "Qi Yang Rong spleen and liver soup" prescription, which states " Two money speculation "; and this book in other places mentioned food, such as mountain cake, only write" yam ", no" pregnant "word.

　　From 1999 to 2003, the state has set up a major scientific and technological project to study and demonstrate the standardization and cultivation of the four major drugs. The project is undertaken by Henan Institute of Chinese Materia Medica and Jiaozuo Municipal Science and Technology Bureau. The results showed that the unit number of yam products contained far more amino acids than the same amount of foreign yam, among them, such as r-aminobutyric acid, which belonged to the genus of yam and other areas. Other yam is basically no yam medicine unique amino acids. The content of allantoin, protein, saponins and iron, calcium and zinc contained in yam yam is much more than that of ordinary yam.

　　As one of the most important tonic materials, Chinese medicine and other commonly used tonic, such as ginseng, Codonopsis, Astragalus, etc., the biggest difference, but also its greatest advantage, without any side effects. So the history of the doctor was evaluated as "warm" and "sex", is "medicine and food homologous" model, that can be used as a normal food to eat, the user is not evasive, suitable for any crowd, any physical, including the elderly, children , Pregnant women and other special population (see 2007 CCTV CCTV "yam - immortal food" program, the Beijing Chinese Medicine Hospital chief physician Wang Guowei comment on the yam medicine). This is why the pregnant yam medicine in the traditional Chinese medicine prescription in the highest frequency of the root causes. Huaiqing Fu another specialty Huaihuang, may be more famous (due to Liu Wei Di Huang Wan reasons), medical value and economic value is higher, but the previous Huaiqing Fu yu yam cultivation and popularity of the amount of production should be greater than Huidi Huang. Pregnant yam medicine can not afford to eat their own, not the heart of yellow. Can replace the grain, this feature in the war or famine age, it is even more important, thousands of years of planting history so that local farmers have some traditional conservative thinking.