Green Ukraine, also known as Zeleny Klyn (Ukrainian: Зелений клин, Zeleny Klyn, Russian: Зелёный Клин, Zelyony Klin, literally: "the green gore/wedge"), also known as Transcathay (Ukrainian: Закитайщина, Zakytajščyna), is a historical Ukrainian name for the land in the Russian Far East area between the Amur River and the Pacific Ocean.
After the Russian Revolution of 1917, the Ukrainian Republic of the Far East was a projected country in the Russian Far East. After the establishment of the Bolshevik Far Eastern Republic on April 6, 1920, Far Eastern areas with an ethnic Ukrainian majority attempted to secede and establish an entity called Green Ukraine. This movement quickly proved abortive.