The Armenian Soviet Socialist Republic, also commonly referred to as Soviet Armenia or Armenia was one of the constituent republics of the Soviet Union in December 1922 located in the South Caucasus region of Eurasia. It was established in December 1920, when the Soviets took over control of the short-lived First Republic of Armenia, and lasted until 1991. Historians sometimes refer to it as the Second Republic of Armenia, following the demise of the First Republic.