Inshū Shichō Gakki (Records on Observations in Oki Province), 1667, is one of the earliest Japanese texts that mention Matsushima (the former Japanese name for Dokdo). It was written by Toyonobu Saitō, a local official of Izumo (eastern part of today’s Shimane prefecture), Japan. It describes Dokdo as follows:

The description above shows that the Oki Islands marked Japan’s northwesternmost boundary and that Dokdo was not included within the scope of Japan’s territory.