Caspian Sea the east often changed course to empty into the Caspian through a now-desiccated riverbed called the Uzboy River, as did the Syr Darya farther north. The Caspian also has several small islands; they are primarily located in the north and have a collective land area of roughly . Adjacent to the North Caspian is the Caspian Depression, a low-lying region below sea level. The Central Asian steppes stretch across the northeast coast, while the Caucasus mountains hug the western shore. The biomes to both the north and east are characterized by cold, continental deserts. Conversely, the climate to the southwest
Caspian Sea around 4 million bbl/day. Additionally, Iran has an estimated 988.4 trillion cubic feet of natural gas, around 16 percent of total world reserves, which makes it to play a key role in the global energy security equation. Russia's economy ranks as the twelfth largest by nominal GDP and sixth largest by purchasing power parity in 2015. Russia's extensive mineral and energy resources are the largest such reserves in the world, making it second leading producers of oil and natural gas globally. The Caspian Sea region presently is a significant, but not major, supplier of crude oil to world markets, based