The waters surrounded by South Korea, North Korea, Russia and Japan have been called the East Sea in Korea but have been widely referred to as the Sea of Japan in Japan and the international community. Back in the early 20th century when international efforts were made to standardize geographical names, Korea, having lost its sovereignty, was not able to actively take part in the process; Japan’s improved international standing also affected the perception of Western cartographers back then.

After Korea’s liberation from Japanese colonial rule, South Korea and Japan failed to reach an agreement on the geographical name for the waters in their 1965 fisheries talks, so they decided to use the terms “East Sea” and “Sea of Japan” in the agreements in their respective local languages. In the 1970s, Korean daily newspapers ran articles stating that what was known as the East Sea in Korea was widely called the Sea of Japan in the international community and calling for corrective measures against such practices. Against this backdrop, South and North Korea, having joined the United Nations together in 1991, officially raised the issue of the East Sea for the first time at the UN Conference on the Standardization of Geographical Names (UNCSGN) in 1992.

Various geographical names reflect the history, culture and identity of individual regions. In the same vein, the term “East Sea” has also been an integral part of Korean long history. The geographical name was first used in The Annals of Three Kingdoms: The Lay of King Dongmyung (Samguksagi Dongmyungwangpyeon; B.C. 59)—700 years ahead of the very first use of Japan as a country name and the origin of the term “Sea of Japan.” The name has been found in various historical records and ancient maps in Korea, including the Inscription of the Great King Gwanggaeto of Goguryo (Gwanggaeto Daewangreungbi; 414), the Map of Eight Provinces (Paldochongdo as part of Sinjeungdonggukyeojiseungram; 1531) and the Comprehensive Map of Korea (Agukchongdo as part of Yeojido; late 18th century).

The ancient map where the waters were first mentioned as the Sea of Japan was the world map drawn by Italian missionary Mateo Ricci in China (1602). This map was brought to Europe and Japan, but the geographic name of the Sea of Japan was not spread there. No Japanese record published up to the late-18th century indicated the use of the name “Sea of Japan.” Rather, Japan perceived the seas as the Sea of Korea, not the Sea of Japan, and used the former name in its ancient maps. As such, Japan’s use of the geographical name “Sea of Japan” has a shorter history than that of “East Sea” which has been in use for the past 2,000 years.

A wide variety of geographical names are used to refer to the waters in ancient Western maps created by European geographers. South Korea and Japan conducted their own surveys on the naming of the waters in ancient Western maps archived in major libraries around the world. Their survey results differ, but they do have two things in common: First, the waters were marked with no geographical name in more than half of maps created prior to the 19th century. This means the international community shared no common perception or understanding as to the naming of the waters. Second, Korea-related geographical names (e.g. Sea of Korea, Eastern Sea, Oriental Sea) were predominantly used in those maps until the 18th century but the use of the Sea of Japan has become prevalent since the mid-19th century. This trend implies that Westerners initially associated the waters with Korea, while the term “Sea of Japan” gained greater ground as Japan’s influence got bigger. Various names had been used to refer to the waters until the 19th century and the use of the name “Sea of Japan” has become frequent since then, but this is not an internationally established practice.

1) Korean search results are based on ancient maps archived in British Library, Cambridge University Library, University of Southern California (USC) East Asian Map Collection, U.S. Library of Congress, National Library of Russia and French National Library

2) Japanese search results are based on ancient maps archived in British Library, Cambridge University Library, French National Library and U.S. Library of Congress

3) The use of the term “Sea of China,” the parallel use of terms “East Sea” and “Sea of Japan” and no indication of any geographical name all included

Source: Northeast Asian History Foundation, 2007, East Sea; Japanese Ministry of Foreign Affairs, 2006, A Historical Overview of the Name “Sea of Japan”

The adoption of the geographical name “Sea of Japan” around the world coincided with Japan’s colonial rule over Korea. The international community held the International Hydrographic Organization (IHO) talks in 1919 and launched the International Hydrographic Bureau (IHB) in 1921 to demarcate waters, standardize marine geographical names and come up with international norms for safety of navigation. Japan sent its delegation to the talks, while Korea was not able to do so as it was under Japanese colonial rule. IHO member countries agreed upon what was discussed in the talks and, after several years of discussion, published a book titled “Limits of Oceans and Seas” in 1929. The book officially adopted “Sea of Japan” as the term referring to the waters between Korea and Japan, catalyzing the subsequent, widespread use of the geographical name in maps published around the world. The second and third editions of the publication were released in 1937 and 1953, with the name “Sea of Japan” remaining in use. At that time, Korea was not able to let its voice heard as it suffered from Japanese colonial rule and the subsequent Korean War (1950-53). In this regard, the Sea of Japan as a geographical name widely used in the international community can be seen as a product of Japanese colonialism.

The East Sea represents waters surrounded by four countries—South Korea, North Korea, Russia and Japan—and therefore entails geographical, economic and political issues such as territorial waters and exclusive economic zone (EEZ). It is not desirable to use the name of a certain country to refer to waters under sovereignty of multiple states. IHO, UNCSGN and other international organizations recommend using a single geographical name for a topographical feature shared by more than two countries in an effort to minimize confusions that may possibly arise if different names are used to refer to the topographical feature. If such is not possible, these varying names should be mentioned in parallel until all parties involved reach an agreement. Korea and Japan currently differ over the use of the terms “East Sea” vs. “Sea of Japan” to refer to the waters between them, so they should use both names until they do reach consensus. The proportion of the world’s major maps using the terms “East Sea” and “Sea of Japan” in parallel has increased from 1.8% in 2000 through 18.1% in 2005 to 23.8% in 2007. This indicates that the international community recognizes the conventional practice of using the term “Sea of Japan” alone as undesirable, with the legitimacy of the geographical name “East Sea” growingly endorsed around the world.

Below are Japan’s major claims over the issues of East Sea vs. Sea of Japan and refutations from Korea’s point of view:

(a) Surveys on ancient Western maps that have been published since the 16th century and are archived in the world’s leading libraries show that the use of the name “Sea of Japan” has been predominant since the early-19th century. This means the geographical name has been widely adopted around the world since then and has nothing to do with Japan’s imperialism or colonialism. Therefore, no geographical name but the Sea of Japan is adequate to refer to the waters.

☞ Numerous geographical names have been used throughout history to refer to the waters, but none of them has ever been fully established. The waters were called in various ways—the East Sea, Oriental Sea, the Sea of Japan—in ancient East Asian maps, while a majority of ancient Western maps placed no name on the waters.

(b) The most common way of naming waters separated from the oceans is to use the name of an island or peninsula that separates the waters from the oceans. In this regard, it is right to refer to the waters separated by the Japanese Archipelago as the Sea of Japan. Prime examples of this include the Gulf of California, the Andaman Sea and the Irish Sea.

☞ Seas are named in various ways: indication of direction; use of the name of adjacent continent, country or city; use of the name of explorer or discoverer; and so forth. There are many examples of marine geographical names for waters separated from oceans that do not derive from the names of archipelagos or peninsulas.

(c) In its reply to a letter from the Japanese government in March 2004, the UN Secretariat asserted, “We at the UN Secretariat make it clear that we would abide by the practice of using the term Sea of Japan alone [to refer to the waters between Korea and Japan]; citing two geographical names (i.e. the East Sea and the Sea of Japan) in parallel is against the UN’s practice and infringes upon its neutrality.” This is the UN’s recognition of the Sea of Japan as the sole official geographical name to refer to the waters. The principle of marking the waters solely as the Sea of Japan has continuously been adopted by IHO and in world maps and textbooks published worldwide.

☞ The very fact that international organizations choose to use a certain geographical name according to their internal principles does not mean they support or approve one country’s stance on the term. A growing number of the world’s leading maps mark the waters between Korea and Japan as the East Sea in parallel with the term Sea of Japan.

These days, some Koreans argue the term “East Sea” should be replaced by “Sea of Korea” which is in sharp contrast to “Sea of Japan.” Koreans have used the term “East Sea” for the last 2,000 years, but the geographical name “Sea of Korea” has never been in use. Many ancient Western and Japanese maps have been found to refer to the waters as the Sea of Korea or the Sea of Joseon. Thus, the East Sea is an endonym and the Sea of Korea an exonym. In the principles of international organizations, a geographical name used by local residents takes precedence over the others. Therefore, the term with historical legitimacy, “East Sea,” should be chosen over “Sea of Japan” which was first used by Westerners.

Surrounded by four nations, the waters should not be called after the name of any single country. It is contradictory to suggest the name “Sea of Korea” as an alternative while claiming that naming shared waters after a certain country (i.e. Japan) is not right. In the past, the waters surrounded by France, the United Kingdom, Germany and Denmark were called the Sea of England, the Sea of Germany and the Sea of Denmark by the respective countries. Since the establishment of IHO, however, the term referring to the waters has been standardized into “North Sea” as they are located in the north of the European Continent. The waters in question are situated in the east of the Eurasia Continent, so it would be desirable to mark them as the East Sea.