No way to know if it was overland (there was no Russia then) or Atlantic, but even if it were overland, it’s likely to have gone by water at least some of the way.
“(there was no Russia then)”
Lol, well of course...
” but even if it were overland, it’s likely to have gone by water at least some of the way.”
Absolutely, I spent a month tracing the rivers and there is an almost continuous water route from the Baltic to the Black Sea. The one blockage is a portage only about 15 miles across from one river to another.
And I believe Heyerdahl’s theory that the Norse originated from Azerbaijan and the Caspian. Which would mean the overland route may have existed long before the Atlantic route. :)