The Nakhichevan Autonomous Soviet Socialist Republic (Azerbaijani: Нахчыван Мухтар Совет Сосиалист Республикасы; Russian: Нахичеванская Автономная Советская Социалистическая Республика), abbreviated as Nakhichevan ASSR (Azerbaijani: Нахчыван МССР; Russian: Нахичеванская АССР), was an autonomous republic within the Azerbaijan SSR, itself a republic within the Soviet Union. It was formed on 16 March 1921 and became a part of the Azerbaijan SSR proper on 9 February 1924.