Sun Wenyin was a medical author in ancient China whose dates, native place and life remain unknown, and the available public information about him is limited. What can be confirmed today is that a single medical work, Dantai Yu'an, is attributed to him. The title suggests a traditional medical book, with "dantai" often associated with medical practice and formularies, and "yu'an" carrying the sense of a treasured or carefully kept record, so the work may have gathered clinical experience together with prescriptions. Because reliable records of the book's transmission and of the author's life are lacking, it is difficult to describe his medical training, teachers, or the places where he practiced, and it would be inappropriate to speculate about his biography. A prudent approach is to regard Sun Wenyin as an ancient physician known through one medical book, to understand his orientation toward clinical practice and the organization of prescriptions through Dantai Yu'an, and to treat both the man and the work with careful textual scholarship when studying traditional Chinese medical texts.
