The Russian conquest of the Caucasus mainly occurred between 1800 and 1864. The Russian Empire sought to control the region between the Black Sea and Caspian Sea. South of the mountains was the territory that is modern Armenia, Azerbaijan, Georgia, and parts of Iran and Turkey. North of the mountains was the North Caucasus region of modern Russia. The difficult conquest of the intervening mountains is known as the Caucasian War. Multiple wars were fought against the local rulers of the regions, as well as the dominant powers, the Ottoman Empire and Qajar Iran, for control. By 1864 the last regions were brought under Russian control.
Early history
Russians first appeared in the Caucasus region in the 9th century when some Rus’ went down the Volga to trade around the shores of the Caspian Sea. This evolved into two great raids in 913 and 943. The last raid seems to have been in 1041. See Caspian expeditions of the Rus'. Also at this time the Rus’ held Tmutarakan on the Taman Peninsula.
From the mid-16th century, there was an isolated group of Cossacks on the Terek River and by around 1550 Cossacks were established on the Don River. Astrakhan was conquered in 1556, giving Russia a base at the north end of the Caspian Sea. They soon made an alliance with Kabardia and built a fort at the mouth of the Sunzha River. After about 1580 Russia disengaged from the Caucasus region for about 200 years, holding Astrakhan and slowly pushing settlement south toward the Black Sea.
During the so-called Russo-Persian War (1651–1653), Persian subjects fought Cossacks on the Sunzha River. In 1688, Stenka Razin raided the Caspian coast. During the Russo-Persian War (1722–1723), Peter the Great conquered the west and south shore of the Caspian, but the land was soon returned when Persia grew stronger. In 1775, after a Russian explorer had died in captivity, Catherine the Great sent a punitive expedition which briefly captured Derbent. During the Persian expedition of 1796, Russia again conquered the west coast of the Caspian, but the expedition was withdrawn when Catherine died.
Underlying all of this was the slow and steady expansion of the Russian population southward from its original heartland in Muscovy. By around 1800, Russia was in a position to push soldiers and colonists into the Caucasus region.
South of the mountains
Russia annexed eastern Georgia in 1800. By 1806, Pavel Tsitsianov had expanded this bridgehead from the Black Sea to the Caspian and gained the Caspian coast. In 1813, Persia was forced to recognize the loss of its northern territory, comprising modern-day southern Dagestan, eastern Georgia, and most of what is now the Azerbaijan. In 1818-1826 Aleksey Petrovich Yermolov tightened the noose around the mountains, but much of this was soon lost. In 1828, Russia took what is modern-day Armenia, Nakhichevan, and Talysh from Persia. The two Turkish wars had few results.
Background
From the days of the Roman Empire, Transcaucasia was usually a borderland between two empires, often centered in Constantinople and Persia. Areas would shift from one empire to the other, their rulers would have varying degrees of independence and the common people suffered much from the wars. Local rulers were often vassals of one empire or the other, but this could vary from complete subjection to a few empty words. Much depended on the size and proximity of the suzerain's army. By around 1750, the area was divided between Turkish and Persian vassals. The western two-thirds was inhabited by Georgians, an ancient Christian people, and the eastern third mostly by Azeris, Turkic Muslims who emerged as a people at an uncertain date. Russia had long held Astrakhan at the north end of the Caspian and was pushing close to the Black Sea. There were also Cossacks along the Terek River who would soon grow into the North Caucasus Line.