The Caucasus, also Caucas or Caucasia (for endonyms, see below), is a geopolitical region at the border of Europe and Asia, and situated between the Black and the Caspian sea. It is home to the Caucasus Mountains, including Europe's highest mountain (Mount Elbrus). Politically, the Caucasus region is separated between northern and southern parts. Geography and ecologyThe northern portion of the Caucasus is known as the Ciscaucasus and the southern portion as the Transcaucasus. The Ciscaucasus contains the larger majority of the Greater Caucasus Mountain range, also known as the Major Caucasus mountains.

It includes Southwestern Russia and northern parts of Georgia and Azerbaijan. The Transcaucasus is bordered on the north by Russia, on the west by the Black Sea and Turkey, on the east by the Caspian Sea, and on the south by Iran. It includes the Caucasus Mountains and surrounding lowlands. All of Armenia, Azerbaijan (excluding the northern parts) and Georgia (excluding the northern parts) are in South Caucasus.The main Greater Caucasus range is generally perceived to be the dividing line between Asia and Europe. The highest peak in the Caucasus is Mount Elbrus (5,642 m) in the western Ciscaucasus in Russia, and is generally considered as the highest point in Europe.

The Caucasus is one of the most linguistically and culturally diverse regions on Earth. The nation states that comprise the Caucasus today are the post-Soviet states Georgia, Armenia, and Azerbaijan. The Russian divisions include Krasnodar Krai, Stavropol Krai, and the autonomous republics of Adygea, Karachay–Cherkessia, Kabardino-Balkaria, North Ossetia, Ingushetia, Chechnya, and Dagestan. Three territories in the region claim independence but are recognized as such by only a handful or by no independent states: Abkhazia, Nagorno-Karabakh and South Ossetia.

The Caucasus is an area of great ecological importance. It harbors some 6400 species of higher plants, 1600 of which are endemic to the region. Its wildlife includes leopards, brown bears, wolves, bison, marals, golden eagles and Hooded Crows. Among invertebrates, some 1000 spider species are recorded in the Caucasus.

The natural landscape is one of mixed forest, with substantial areas of rocky ground above the treeline. The Caucasus Mountains are also noted for a dog breed, the Caucasian Shepherd Dog