Original: The Transcaucasus is bordered on the north by Russia, on the west by the Black Sea and Turkey, on the east by the Caspian Sea, and on the south by Iran.
Simplified: The Caucasus or Caucasia is a region in Eurasia bordered on the south by Iran, on the southwest by Turkey, on the west by the Black Sea, on the east by the Caspian Sea, and on the north by Russia.