Sakhalin is a region located in the Russian Far East. It is made up of both the Sakhalin and Kuril Islands. The area itself is approximately 33,600 square miles, and the vast majority of the people who live there are ethnic Russians. There are also some people who identify as Koreans, but the area is sparsely populated when compared to the rest of Russia. In addition, there is some debate regarding the borders of the region between Japan and Russia. Even though Sakhalin is a long way away from Moscow, Russia still claims sovereignty over the territory.
During the past few decades, the population on Sakhalin has been steadily going down. For example, in 1989, it was estimated that there were more than 700,000 people living there. Then, by the time of the 2002 census, it was estimated that there were approximately 546,000 people living there. Finally, during the most recent census, the estimate had dropped to under 500,000 people. There are a number of reasons why the population in the area might be dropping. For example, some people are concerned about the economy, so they have decided to go elsewhere. There are other people who may be realizing that life is better in Japan, so they could be migrating south into the Japanese islands. Regardless, the population in the area has been steadily declining during the past few decades.
For the vast majority of its history, Sakhalin has been claimed by the Japanese. The Japanese cemented their claim on the area during the Imperial era, leading up to World War 2. At the end of World War Two, Russia claimed Sakhalin from Japan. The United States was already in the process of planning a Japanese invasion, and the Japanese empire had been significantly weakened by the latter stages of 1945. As a result, following the surrender of Germany, the Soviet Union quickly took its resources from the Western Front and moved them to the Eastern Front, launching an invasion of Japan in August of 1945. Because the Japanese Empire had been significantly weakened, it did not take Russia long to conquer Sakhalin and the Kuril Islands. After the end of the war, the Russian soldiers did not leave, claiming the area for Russia.
Yes, the Japanese still claim Sakhalin and the Kuril Islands. With the Treaty of San Francisco, which was signed in 1952, Japan renounced the portion of Sakhalin and all islands adjacent to it While Japan has recognized Sakhalin as being part of Russia, it does not do the same thing with the Kuril Islands. Instead, it claims the Kuril Islands as part of its Northern Territories, despite Russia doing the same. Even though it is unlikely that this dispute will lead to a major conflict, it is something that has not been resolved.