When IHO released 'Limits of Oceans and Seas' in 1929, 'Sea of Japan' began to be widely known, and the Korean peninsula was under Japanese occupation. But, actually, 'East Sea' has been the name for 2000 years and not only in Korea. In world maps and even old Japanese maps, they also called it 'East Sea' or 'Joseon Sea'.
When IHO released 'Limits of Oceans and Seas' in 1929, 'Sea of Japan' began to be widely known, and the Korean peninsula was under Japanese occupation. But, actually, 'East Sea' has been the name for 2000 years and not only in Korea. In world maps and even old Japanese maps, they also called it 'East Sea' or 'Joseon Sea'.