Tendaisan ki (Tiantaishanji in Chinese) is a geographical description of the Chinese holy mountain, Tendaisan (Tiantaishan in Chinese), located in Zheijiang Province. The author, Xu Lingfu, was a Taoist who lived in seclusion in order to discipline his mind and body. Xu lived on Tendaisan from 815 to 825, where he wrote this book. A Japanese monk studying in China may have copied the original in China or he may have brought a copy back to Japan, after which it was lost. This manuscript, held in the National Diet Library, is the only copy of this book and the only remaining geographical description from the Tang dynasty. The writer of the manuscript is unidentified. At the upper right of the title someone has added "Written by Annen." Annen (circa 841−circa 915) was a great scholar of the Tendai sect of Buddhism in Japan. There is no evidence, however, that he made this copy. After the text of Tendaisan ki,that of Busso tōki taikan den (Fozu tongji diguan zhuan in Chinese) by Zhipan has been added in another hand. When the scholar Li Shuchang reprinted 26 Chinese rare books that are known to survive only in Japan (as theGuyi congshu series in the tenth year of the Guangxu period of the Qing dynasty, 1884), he included this book as one of the texts.