The two rivers that lie between the Caspian Sea and the Black Sea are the Don River and the Volga River. The Volga River flows into the Caspian Sea, while the Don River flows into the Sea of Azov, which is connected to the Black Sea. These rivers are significant for transportation and irrigation in the region.
Caucasus
The Caspian Sea lies between the Aral Sea and the Black Sea.
The Aegean Sea.
Caspian Sea
The three countries located between the Black Sea and the Caspian Sea are Georgia, Azerbaijan, and parts of Russia. Georgia lies to the northwest of Azerbaijan, which directly borders the Caspian Sea to the southeast. Some regions of southern Russia also stretch between these two seas, particularly in the North Caucasus area.
Caspian Sea lies between Turkey and Kazakhstan, however Turkey doesn't directly border the Caspian Sea. The countries that border the Caspian Sea are: Azerbaidjan, Iran, Kazakhstan, Russia, Turkmenistan.
the Caspian Sea
The Caspian Sea lies to the east of the Black Sea.
The Black Sea is completely landlocked.
Aral Sea
The physical feature that lies between the Muslim Empire's Northern border is the Caucasus Mountains. These mountains stretch between the Black Sea and the Caspian Sea, forming a natural barrier between the Muslim Empire and the surrounding regions to the north.
Garabogazköl Aylagy is a lake to the east of the Caspian Sea.