The invasion of 1920 began a seventy-one-year period under total political and economic control of the state that became the Soviet Union in 1922. The borders and formal status of Azerbaijan underwent a period of change and uncertainty in the 1920s and 1930s, and then they remained stable through the end of the Soviet period in 1991.

Determination of Borders and Status

In late 1921, the Russian leadership dictated the creation of a Transcaucasian federated republic, composed of Armenia, Azerbaijan, and Georgia, which in 1922 became part of the newly proclaimed Soviet Union as the Transcaucasian Soviet Federated Socialist Republic (TSFSR). In this large new republic, the three subunits ceded their nominal powers over foreign policy, finances, trade, transportation, and other areas to the unwieldy and artificial authority of the TSFSR. In 1936 the new "Stalin Constitution" abolished the TSFSR, and the three constituent parts were proclaimed separate Soviet republics.

In mid-1920 the Red Army occupied Nakhichevan, an Azerbaijani enclave between Armenia and northwestern Iran. The Red Army declared Nakhichevan a Soviet socialist republic with close ties to Azerbaijan. In early 1921, a referendum confirmed that most of the population of the enclave wanted to be included in Azerbaijan. Turkey also supported this solution. Nakhichevan's close ties to Azerbaijan were confirmed by the Russo-Turkish Treaty of Moscow and the Treaty of Kars among the three Transcaucasian states and Turkey, both signed in 1921.

Lenin and his successor, Joseph V. Stalin, assigned pacification of Transcaucasia and delineation of borders in the region to the Caucasian Bureau of the Russian Communist Party (Bolshevik). In 1924, despite opposition from many Azerbaijani officials, the bureau formally designated Nakhichevan an autonomous republic of Azerbaijan with wide local powers, a status it retains today.

The existence of an Azerbaijani majority population in northern Iran became a pretext for Soviet expansion. In 1938 Soviet authorities expelled Azerbaijanis holding Iranian passports from the republic. During World War II, Soviet forces occupied the northern part of Iran. The occupiers stirred an irredentist movement fronted by the Democratic Party of Azerbaijan, which proclaimed the communist Autonomous Government of Azerbaijan at Tabriz at the end of 1945. The Western powers forced the Soviet Union to withdraw from Iran in 1946. Upon the subsequent collapse of the autonomous government, the Iranian government began harsh suppression of the Azerbaijani culture. From that time until the late 1980s, contacts between Azerbaijanis north and south of the Iranian-Soviet border were severely limited.

Data as of March 1994