>They are saying "Jews", I am thinking Israel instead. Perhaps tribe of Dan?
Good Morning Blam.
Anything "in southern Russia between the Black and Caspian seas" is fodder for discussion about The Lost Tribes of Israel. They were certainly there by the Millions after they escaped the Assyrian Captivity ~600 BC.
However there's not a lot of evidence to suggest they stayed around to see how it was all going to play out. These 6+ MILLION people, now known as The CELTS, moved out quickly in waves to the West and Northwest, to become the Europeans and Americans of today.
This Viking article talks about 830 AD, so I think any members or relatives of the original Tribe of Dan (or any other tribe) were long gone, long before. But since the Vikings (especially Swedish Vikings) are known to have come to this region during their explorations and trading with the Mediterranean area, it is quite possible some of the Lost Tribe Israelites (not Jewish) returned.
Some people believe all Scandinavians came from the Tribe of Dan (as in Danmark and many other good examples based on Dan). But there are also other good theories as to which of the Tribes spawned which Europeans.
There are other well-founded theories that link the Scandinavians (Norse and Svensk) directly with Pre-Celts (via the Caucasus), Israelites who left Egypt by sea ~ a hundred years before the Exodus by land.