This editorial will provide answers as to why Japan’s assertion is not valid and why both names, “East Sea” and “Sea of Japan,” should be used concurrently to refer to the sea area in question. These answers will be set out, with historical evidence of the use of the name “East Sea” and the logical basis to support the legitimacy of the international use of the name “East Sea.”
Approximately eighteen Japanese maps referred to the sea area between Korea and Japan as “Sea of Joseon.” Examples include the Map of Asia (亞細亞全圖) drawn by Katsuragawa Hoshu in 1794 and the Simplified Map of Japan’s Periphery (日本邊界略圖) by Takahashi Kageyasu in 1809. Additional examples are the New World Map (新製輿地全圖) drawn by Mitsukuri Shogoin in 1844 and Japan’s Northeast Marginal Boundary Map (本邦西北邊界略圖) by Yasuda Raishu in 1850. Furthermore, the Collection of Korean Treaties, containing documents of diplomatic agreements between Korea and Japan in 1883, designated the waters as the “Sea of Joseon.”
In a brochure distributed by the Japanese Foreign Ministry, Japan insists that since the sea was described as “Sea of Japan” in “La Perouse: Chart of Discoveries made in 1787 in the Seas of China and Tartary,” the name began to be used by many European mapmakers and became well established internationally in the late 18th and early 19th century.
After it examined a number of Western maps produced since the 16th century, Japan claimed that its position has greater historical validity since old Western maps evidence more frequent usage of the term “Sea of Japan” from the early 19th century onwards.
While this may be Japan’s claim, the frequent use of the name in ancient Western maps is not enough to support Japan’s position that the name “Sea of Japan” was established around the 19th century. It should be pointed out that 72.8% (1,088 out of 1,495) of the old maps held by the French National Library (Bibliotheque Nationale de France) and 50.1% (223 out of 445) of the maps drawn up before the 19th century held by the US Library of Congress do not even indicate a name for the sea area in question. This shows that there was no international consensus or common understanding regarding the name of the sea prior to the 19th century. More importantly, no international regime on the standardization of geographical names was in place at the time.