Bolshoy Ussuriysky Island

Bolshoi Ussuriysky Island (Russian: о́стров Большо́й Уссури́йский), or Heixiazi Island (simplified Chinese: 黑瞎子岛; traditional Chinese: 黑瞎子島; pinyin: Hēixiāzi Dǎo), is a sedimentary island at the confluence of the Ussuri and Amur rivers. It is divided between the People's Republic of China (PRC) and Russia. It has an area of about 327 to 350 km² and is bounded closely by Yinlong Island (Tarabarov Island), and over ninety islets (in Chinese, Heixiazi may refer only to the large island or to the island group collectively). Its position at the confluence of the Amur and the Ussuri and right next to the major Russian city of Khabarovsk, has given it great strategic importance.

Until 2004, Bolshoy Ussuriyskiy Island was the site of a territorial dispute between China and Russia. The Soviet Union occupied Bolshoy Ussuriyskiy and Yinlong Islands in 1929, but this was not accepted by China. While Russia governed the islands as a part of Khabarovsk Krai, China claimed them as a part of Fuyuan County, Heilongjiang province; the easternmost part of China.

From 1931 to 1945 Bolshoy Ussuriysky was claimed as part of Japan's puppet state of Manchukuo and was known to the Japanese as Kanchazu Island. In June 1937 Bolshoy Ussuriyskiy was briefly occupied by Soviet sailors til they were driven off by Japanese and Manchukuoan troops in the Kanchazu Island incident

The difficulty in settling this dispute involved competing interests between Russia and China. To settle the boundary along the lines claimed by China would have moved settled parts of the city of Khabarovsk into China. However, to grant the island to Russia would have put the boundary along a waterway that is not navigable by large ships restricting Chinese ability to move ships along the Amur.

...
Wikipedia