Mountain Autonomous Soviet Socialist Republic or Mountain ASSR ( Gorskaya ASSR) was a short-lived autonomous republic within the Russian SFSR in the Northern Caucasus that existed from January 20, 1921 to July 7, 1924.
The Mountainous Republic of the Northern Caucasus was created on parts of Kuban and Terek Oblasts by the indigenous nationalities after the Russian Revolution; however, Soviet rule was installed on this territory after the Red Army conquered the Northern Caucasus in the course of the Russian Civil War, and the former republic was transformed into the a Soviet one. The area of the republic was over , and the population was about 800,000. It comprised six okrugs: Balkar, Chechen, Kabardian, Karachay, Nazran (Ingushetia), and Vladikavkaz Okrug (Ossetia) and had two cities: Grozny and Vladikavkaz. In addition, a special autonomy was provided to the Terek Cossacks: Sunzha Cossack Okrug, which included a large enclave in northern Ingushetia, and a smaller one bordering Grozny. Its boundaries approximated those of classical Zyx.
The ASSR did not exist in its original state very long. Already on September 1, 1921 Kabardin Okrug was split from the ASSR as separate Kabardin Autonomous Okrug, subordinated directly to the RSFSR. Next came Karachay Okrug, which was transformed into Karachay Autonomous Okrug on January 12, 1922; Balkar Okrug, which was transformed into Balkar Autonomous Okrug on January 16, 1922; and Chechen Okrug, which was transformed into the Chechen Autonomous Oblast on November 30, 1922.
By the Decree of the VTsIK of July 7, 1924, the remaining territory of the ASSR was partitioned into the North Ossetian Autonomous Oblast and the Ingush Autonomous Oblast. The Sunzha Cossack Okrug and the city of Vladikavkaz were directly subordinated to the VTsIK until October 17, 1924 when North Caucasus Krai was formed and integrated all of the former ASSR in addition to those two units.