One of the oddities of history is the tribal migrations from Central Asia into Europe that lasted for more than a millennia. From the 5th Century BC barbarians of Ancient Greece (Scythia) to the Vandals, Goths and Huns that ended the Western Roman Empire to the Mongols (1200s AD) that conquered Eastern Europe and Islamic Persia, it seems that the usual movement went from east to west.
The Turks also originally from Central Asia reached Vienna by the early 16th century. Don’t forget the Magyars who are still in Hungary or the Alans. One of my favorite characters is the Bulgar Khan Krum who drank from a gold inlaid skull of a Byzantine Emperor.
Don’t stop at the shores of Europe. Think of the East-
West migration pattern from Europe to the Americas and then across those continents to the Pacific shores.
I wrote a long epic poem once that proposed a theory that there is a inherent tribal instinct to follow the sun.
Of course the Polynesians are the exception that either founders the theory or proves the rule.