The tribes of Israel were exiled by the Assyrians to three places; Halah (Khalakh), the confluence of the river Gozan and the cities of the Medes. The first two places are beyond the mountains of the Caucasus. Khalakh, of which it is some-times said that its location is unknown (Graetz) was Colchis, the south-eastern coast land of the Black Sea. To Colchis Jason sent the legendary Argonaut expedition to bring back the Golden Fleece.
A Jewish community lives there from ancient times, claiming descent from the exiled Ten Tribes. Also in the Georgian mountains live Mountain Jews with ancient customs, also claiming descent from the Ten Tribes. See about them Ben-Zvi, The Exiled and the Redeemed.
Caspian Sea comes from the Hebrew word caspi, or silvery. Rostov from Rosh Tov (good estuary), Don from Dan, also Donai (possibly also Dnieper and Dniester) all to memory of Dan, the holy city of the Ten Tribes. A large number of the Israelites were exiled by Sargon II over the Caucasian mountains to Southern Russia.