KoreaKorean Hanguk or Choson, region and historic country, E Asia. A former country in E Asia (85,049 sq mi/220,277 sq km), now divided into two separate countries, North Korea and South Korea. A peninsula, 600 mi (966 km) long, Korea separates the Sea of Japan on the east from the Yellow Sea. On the south it is bounded by the Korea Strait (connecting the Sea of Japan and the Yellow Sea) and on the north its land boundaries with China and Russia.