1. Korean Territorial Claims Proven by Japanese Historical Sources
“Bakufu-sen Keichō Nihon chizu” (幕府撰慶長日本地圖): western Japan (1640)The Edo shogunate ordered that this map be compiled. It shows the Oki Islands marked as the northwestern-most territory. The other four maps commissioned by the government show the same territory. The Edo shogunate considered Dokdo as part of Joseon territory.
From the seventeenth century to the mid-nineteenth century Dokdo and Ulleung were called Matsushima and Takeshima, respectively, in Japan. The oldest Japanese source that mentions Dokdo is “Records on Observations on Oki” (“Onshū shichō gōki,” 1667). This text was written by Saitō Hōsen, who was a government official of Matsue domain (in present-day Shimane Prefecture) and who visited the Oki Islands on behalf of the daimyo of Matsue domain. In this text Saitō wrote, “Murakawa (a merchant who traded at Ulleungdo) received approval from the government and sent a large ship to Iso Takeshima (Takeshima, Ulleungdo).” This statement shows that Saitō recognized Ulleungdo as a foreign land to which trade ships sailed.
In “Records on Observations on Oki” is written, “Northwest of Japan, we make this land to be the boundary,” meaning that the Oki Islands were the northwestern territorial limit of Japan. In addition, the Edo shogunate published Japanese maps in five editions. Of these, the first four maps were based on regional maps and the fifth one was compiled from surveys conducted by Inō Tadataka under the order of the shogunate. These five government-commissioned maps compiled by the Edo shogunate excluded Dokdo from the territory of Japan.
A chapter in Kokutai ki entitled “Records on Observations on Oki”Legend: “If you proceed northwest you will reach Matsushima (松島; that is, Dokdo) in two days and one night. And you will reach Takeshima (竹島; that is, Ulleungdo) in one more day. These two places are uninhabited islands. From there you can see Joseon, just as you can see Oki from Unshū, which is part of Matsue domain.” Thus, the land (that is, the Oki Islands) northwest of Honshu Island is the territorial boundary.