Sakhalin Koreans are Russian citizens and residents of Korean descent living on Sakhalin Island, who can trace their roots to the immigrants from the Gyeongsang and Jeolla provinces of Korea during the late 1930s and early 1940s, the latter half of the Japanese ruling era.

Korean is the native language for about 81 million people, mostly of Korean descent. It is the official and national language of both North Korea and South Korea. The language has notable differences in each of the Koreas, in part owing to different official standardizations of the language. They are still largely mutually intelligible, however. South Korean newspaper Daily NK has claimed North Korea criminalizes the use of the South's standard language with the death penalty, and South Korean education and media often portray the North's language as alien and uncomfortable.