The Caspian Sea was a sea on Earth.
Caviar was a delicacy from the Caspian Sea. (TNG: "Sins of The Father")
Retroactive continuity; A 20th century-era statistical map of Europe, Africa, and Asia was stored in the USS Enterprise library computer in 2254. On this map, a body of water, located in Asia, was labeled as the "Caspian Sea". This map was among the materials viewed by the Talosians when they scanned the Enterprise computer. (TOS: "The Cage")