Caspian sea who shoreline forms a natural boundary to the east. The Caspian Sea is the largest inland body of water on Earth by area. It is the worlds largest lake or full fledged sea.The Caspian sea is boarded by Russia.
the greater Caucasus Mountain range to the north. This mountain range is in the middle of the Black Sea and the Caspian Sea.This region is divided by Russia, Azerbaijan, and other countries.