Ishinbo was compiled by TANBA no Yasuyori, who was a court physician and acupuncturist in the Heian period. It is the oldest medical book that exists in Japan.
It consists of 30 volumes. It covers medical ethics, general medicine, therapies for diseases, hygiene, curing methods, the art of medicine, medical philosophy, and bochujutsu (sexual art). The main text is entirely written in Chinese with citations from a large number of medical books that existed during the Tang Dynasty. The book is regarded as philologically very important in that it can allow us to reconstruct many books that have been lost from the earth.
So-called 'classics' in East Asia were used as sources of citations for new books. Which is to say, writing a new book meant re-editing selected passages from a set of old books.
Up until the period of the Ming and Qing Dynasties, most books on acupuncture were re-edited versions of Huangdi Neijing (The Yellow Emperor's Inner Canon) and other classical works. In other words, the East-Asian authors avoided writing anything that had no historical sources. That is how they cited classical texts.
Ishinbo is very exemplary in this respect.
Ishinbo was presented by the editor TANBA no Yasuyori to the court in 984. It had been housed in the court until 1554, when it was given by Emperor Ogimachi to the Nakarai family, who served as Tenyaku no kami (the head of Tenyaku ryo, the Bureau of Medicine). It is also referred to as having been secretly kept by the Tanba family. Yet at least in the Taki family, whose line descended from the Tanba family (and who held the position of supreme physician in the Edo bakufu [Japanese feudal government headed by a shogun] alongside the Nakarai family), most of it was presumably lost by the end of the Edo period. The original text of 'Ishinbo' that the Edo bakufu had Taki revise at the end of the period was based on the manuscript that had been handed down in the Nakarai family. This Nakarai manuscript was sold by the family to the Agency of Cultural Affairs in 1982. It has been designated as a national treasure since 1984.
Not only in medicine but also in Japanese historical linguistics and calligraphy it has been regarded as highly important, since it includes declensional kana endings and reading guides in the Heian and Kamakura periods.