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
Caspian expeditions of the Rus' in 913. A fleet of 500 ships reached the southern shores of the Caspian Sea through the country of the Khazars. In order to secure a peaceful passage through the land of the Khazars, the Rus' promised the Khazars half of their spoils. They sailed down the Dnieper River into the Black Sea, then into the Sea of Azov, then up the Don River past the Khazar city of Sarkel, and then by a portage reached the Volga, which led them into the Caspian Sea. The Rus' attacked in the Gorgan region around Abaskun, as well as Tabaristan, pillaging the