The most famous iron bar yam in Jiaozuo, Henan is Wenxian. Tieguang yam from Wen County, Jiaozuo, Henan, is delicate and smooth, with a unique flavor. It is a good medicine and delicacy for both medicinal and food purposes. Tiegun yam is one of the many varieties of yam. There are traces of rust on the iron yam. According to different geographical locations, it is divided into two types: sandy soil and loin soil near the Yellow River.