The Greeks were afraid to go into the Black Sea, believing it was the end of the world. It was the place Zeus chained Prometheus as punishment for bringing fire to mankind. When the Greeks first began exploring this region, they were surprised to find humans not gods.
What's more surprising is that these people still live in this isolated region, long after the Greeks have left.
The most remote area is called Svaneti. These are the people who put sheepskins in glacial runoff to gather gold dust... thus the golden fleece. They still speak a proto language that hasn't changed for over 5000 years. They live in 12th century medieval towers and perform pagan animal sacrifice on 8th century stone alters.
This mountain range was the divide between the mortal and immortal worlds. Prometheus was chained to this mountain when he offended the gods for bringing fire to the mortal world.