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 Sea region. There are similar tensions between Azerbaijan and Turkmenistan (the latter claims that the former has pumped more oil than agreed from a field, recognized by both parties as shared). The Caspian littoral states' meeting in 2007 signed an agreement that bars any ship not flying the national flag of a littoral state from entering the sea. Negotiations among the five littoral states have been ongoing, amidst ebbs and flows, for the past 20 years, with some degree of progress being made at the fourth Caspian Summit held in Astrakhan in 2014. The Caspian Summit is a head of state-level