Caspian Sea and a Pleistocene stage, that includes glaciation cycles and the creation of the present Volga River. During the first stage, the Tethys Sea had evolved into the Sarmatian Lake, that was created from the modern Black Sea and south Caspian, when the collision of the Arabian peninsula with Western Asia pushed up the Kopet Dag and Caucasus Mountains, setting definitive south and west boundaries to the Caspian basin. This orogeneic movement was continuous throughout the years, while Caspian was regularly disconnecting from the Black Sea. In the late Pontian, a mountain arch rose across the south basin and divided it
Black Sea–Caspian Steppe Azov broke off and formed the Lesser Nogai Horde, a name that gradually went out of use. Around 1630 the Kalmyks migrated west from Dzungaria and occupied the land around the north end of the Caspian Sea, driving the Nogais south and west. In 1771 a significant part of them returned to Dzungaria and the Nogais returned east and north. A few Russians were on the lower Terek by about 1520 and Cossacks were somewhere on the Don by 1550. In 1556 Russia took Astrakhan and interacted with Kabardia for a few years before losing interest in the area south