Wikipedia
Sakhalin (, ) is a large Russian island in the North Pacific Ocean, lying between 45°50' and 54°24' N. It is Russia's largest island, and is administered as part of Sakhalin Oblast. Sakhalin, which is about one fifth the size of Japan, is just off the east coast of Russia, and just north of Japan.
The indigenous peoples of the island are the Ainu, Oroks and Nivkhs. Sakhalin was claimed by both Russia and Japan over the course of the 19th and 20th centuries. These disputes sometimes involved military conflict and divisions of the island between the two powers. Russia has held all of the island since seizing the Japanese portion in the final days of World War II in 1945. (Japan no longer claims any of Sakhalin, though it does claim some nearby islands.) Most Ainu on Sakhalin moved to Hokkaido when the Japanese were displaced from the island in 1949.