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 of Islam led to the Arab-Khazar Wars (642-737) and in 737 Arabs briefly reached the lower Volga. The Pechenegs (c. 800 – 1100) moved from north of the Caspian into this area perhaps around 850. They pushed or were pushed westward and were eventually broken up in wars with the Byzantines. Behind them came the Cumans – Kipchaks (?-1241), two peoples that are hard to distinguish. Like the Pechenegs they continued west and fought the Rus’ and Byzantines. The appearance of the Kipchaks may mark the final establishment of Turkic languages north of the Black Sea. After the Mongols conquered