The Azerbaijan SSR was a republic within the Soviet Union from 1920 until 1991. It was established after the Bolshevik Revolution and was part of the larger Soviet socialist system. The capital city was Baku, known for its oil production and cultural significance. During its existence, the Azerbaijan SSR underwent significant industrialization and urbanization. The republic was home to various ethnic groups and had a rich cultural heritage, including contributions to literature, music, and art. In 1991, Azerbaijan declared independence following the dissolution of the Soviet Union.