Naming the Sea of Japan
The Sea of Japan separates Japan from Asia.
by Bob Kerstetter
The Sea of Japan physically and symbolically separates Japan from the Asian continent. It lies to the west of Japan, dividing Japan from Russia, the Republic of Korea (South Korea) and the Democratic People's Republic of Korea (North Korea). The border of China comes within several kilometers of the sea, but does not touch it.
While scholars differ as to when the sea obtained its name, a survey of books and references* published in the West between 1800 and 1859 shows numerous works identifying the body of water as the Sea of Japan. These books appeared during the time when Japan remained isolated from other nations—except the Netherlands, Korea and China—and held little international influence. The information for these books came from the explorations of Western seafarers between 1540 and 1850, before American sea captain Matthew Perry opened Japan to trade and diplomatic relations with the West.
South Korea names this body of water the East Sea. North Korea calls it the East Sea of Korea. Russia and China refer to it as the Japan Sea. The International Hydrographic Organization—the official naming organization—names the body of water Sea of Japan. A few modern maps use two names—Sea of Japan and East Sea.
This map shows the body of water labeled Sea of Japan. It comes from the book Japan as it was and is by Richard Hildreth, published by Phillips, Sampson and Company, Boston, 1855. The publisher released revisions of this book until the first decade of the Twentieth Century.
*Early to mid 19th Century works identifying the Sea of Japan include:  Hildreth, Richard, Japan as it was and is, Phillips, Sampson and Company, Boston, 1855;  Malte-Brun, C. Universal geography: or A description of all parts of the world, on a new plan, according to the great natural divisions of the globe. A. Finley, Philadelphia, 1827.  Watts, T. Japan and the Japanese: from the most authentic and reliable sources. J.P. Neagle, New York, 1852.;  Hildreth, R. Japan as it was and is. Phillips, Sampson and company, Boston, 1855.;  MacFarlane, Charles, Japan: an account, geographical and historical, from the earliest period at which the islands composing this empire were known to Europeans, down to the present time, and the expedition fitted out in the United States, etc, S. Andrus & son, Hartford, 1856.