Caspian Depression
Between 1860 and 1920, "Dagestan" was referred to as Dagestan Oblast, corresponding to the southeastern part of the present-day republic. The current borders were created with the establishment of the Dagestan Autonomous Soviet Socialist Republic in 1921, with the incorporation of the eastern part of Terek Oblast, which is not mountainous but includes the Terek littoral at the southern end of the Caspian Depression.