The Mountainous Republic of the Northern Caucasus (MRNC), also referred to as the United Republics of the North Caucasus, Mountain Republic, or the Republic of the Mountaineers, was a state in Eurasia and encompassing the entirety of the North Caucasus that emerged during the Russian Civil War and existed from 1918 to 1919. It formed as a consolidation of various Caucasian ethnic groups, including the Abkhazians, Abazins Circassians, Chechens, Karachays, Ossetians, Balkars, Ingush, and Dagestanis.

The North Caucasus, or Ciscaucasia, is a region in Western Asia governed by Russia. It constitutes the northern part of the wider Caucasus region, which forms the natural border between Europe and West Asia. It is bordered by the Sea of Azov and Black Sea to the west, the Caspian Sea to the east, and the Caucasus Mountains to the south. The region shares land borders with the South Caucasus countries of Georgia and Azerbaijan. Krasnodar is the largest city within the North Caucasus.