Korea has trouble fabricating a "historical precedent" for the name East Sea because there is no historical western maps that designate the Sea of Japan as "East Sea." By contrast, some maps show the East China Sea as "Eastern Sea." Here is the list of those maps I found.
| Date | Title | Image | Designation |
|---|---|---|---|
| 1730 | J.M. Haas: Regni Sinae vel Sinae Propriae | raremaps.com | TONG HAI OU MARE ORIENTALS |
| 1739 | J.M. Hass: Imperii Russici et Tartariae Universae tam majoris et Asiaticae quam minoris et Europaeae Tabula | Osaka Univ. | TONG HAI Mare Orientals |
| 1775 | Jo. Roberts: The empire of China, with its principal divisions | USC | EASTERN OCEAN |
| 1785 | J. Murray: A map of the empire of China | USC | EASTERN OCEAN |
| 1792 | China, from d'Anville | USC | EASTERN OCEAN or CHINESE SEA |
| 1813 | J.C.Russell: Asia | antiqueprints.com | EASTERN SEA |
| 1815 | J. Thomson: Corea and Japan | Osaka Univ. | EASTERN SEA |
| 1816 | W.Milton: Asia | antiqueprints.com | EASTERN SEA |
| 1822 | Asia | USC | EASTERN SEA |
| 1834 | John Dower: China and Japan | earlymaps.com | EASTERN SEA |
| 1838 | Sidney Hall: Asia | antiqueprints.com | EASTERN SEA |
| 1840 | William Lizars: China | raremaps.com | EASTERN SEA |
| 1843 | R.Scott: Asia | antiqueprints.com | EASTERN SEA |
| 1843 | R.Scott: China | antiqueprints.com | TUNG HAI OR EASTERN SEA |
| 1844 | William Johnston; Alexander Keith Johnston: China | Osaka Univ. | EASTERN SEA |
| 1845 | published by George Philip & Son: Asia | antiqueprints.com | EASTERN SEA |
| 1845 | published by George Philip & Son: China | antiqueprints.com | EASTERN SEA |
| 1851 | John Tallis: Illustrated Atlas | HKUST (PDF) | EASTERN SEA |
| 1858 | J. H. Colton & Co: Asia | USC | EASTERN SEA |
| 1865 | Adrien-Hubert Brue: Carte general de l'Empire Chinois et du Japon. | Osaka Univ. | MER BLEUE OU ORIENTALE (TONG-HAI) |
| 1865 | Edward Weller: The Chinese Empire | antiqueprints.com | TUNG HAI OR EASTERN SEA |
| 1869 | A & C Black : China | raremaps.com | TUNG HAI OR EASTERN SEA |
| 1870 | August Petermann: China(Östr. Theil), Korea und Japan | Osaka Univ. | OSTCHINESISCHES MEER (chin. TUNG HAI) |
| 1888 | Encyclopaedia Britannica | Multiple Digression | EASTERN SEA |
| 1892 | Americanized Encyclopaedia Britannica, Vol.1: Asia | UT Autsin | EASTERN SEA |
| 1894 | Wm. M. Bradley: China / Japan | USC | TUNG HAI OR EASTERN SEA |
| 1896 | the Scottish Geographical Magazine. Published by the Royal Scottish Geographical Society and edited by James Geikie and W.A. Taylor. Volume XII: Formosa | UT Austin | EASTERN SEA |
| ? | T. Clerk Edinr: China | USC | TUNG HAI OR EASTERN SEA |
The East China Sea is shown as 
(Dong Hai), whose meaning is "East Sea." Of course, the Sea of Japan is shown as "Ri Ben Hai" (Ri Ben = Japan, Hai = Sea).
What will happen to Chinese people if the term East Sea become an international geographic name? They will translate it into Chinese, but there is no choice but (Dong Hai) for "East Sea." Then the two neighboring seas will be called the same name!
