By the time of the first century BC, Zoroastrianism had become the dominant religion of the region; however, the region would go through two other religious transformations.Owing to the strong rivalry between Persia and Rome, and later Byzantium, the latter would invade the region several times, although it was never able to hold the region.The peoples of the northern and southern Caucasus tend to be either Sunni Muslims, Eastern Orthodox Christians and Armenian Christians.Twelver Shi'ism has many adherents in the southeastern part of the region, in Azerbaijan which extends into Iran.All of Armenia, Azerbaijan (excluding the northernmost parts) and Georgia (excluding the northernmost parts) are in the South Caucasus.The watershed along the Greater Caucasus range is generally perceived to be the dividing line between Europe and Southwest Asia.founded the Kingdom of Alania, that flourished in the Northern Caucasus, roughly in the location of latter-day Circassia and modern North Ossetia–Alania, until its destruction by the Mongol invasion in 1238–39.
The Caucasus region is separated between northern and southern parts – the North Caucasus (Ciscaucasus) and Transcaucasus, respectively.
The Transcaucasus region and southern Dagestan were the furthest points of Persian Parthian and later Sasanian expansions, with areas to the north of the Greater Caucasus range practically impregnable.
The mythological Mount Qaf, the world's highest mountain that ancient Iranian lore shrouded in mystery, was said to be situated in this region, making the Caucasus the highest limit of the world.
The Greater Caucasus mountain range in the north is within the Russian Federation, while the Lesser Caucasus mountain range in the south is divided between several independent states, namely Georgia, Armenia, Azerbaijan. Yuyukin, is a compound word that can be interpreted as the "Seagull's Mountain" (καύ-: καύαξ, καύηξ, ηκος ο, κήξ, κηϋξ "a kind of seagull" the reconstructed *κάσος η "mountain" or "rock" richly attested both in place and personal names.) According to German philologists Otto Schrader and Alfons A.
The Transcaucasus extends eastwards to the Caspian Sea and northwestern Iran, and extends westwards into northeastern Turkey. Nehring, the Ancient Greek word Καύκασος (Kafkasos) is connected to Gothic Hauhs ("high") as well as Lithuanian Kaũkas ("hillock") and Kaukarà ("hill, top").