If you look at human genetic populations, particularly several haplogroups prevalent among the first peoples to re-settle Europe after the ice age, and the Midd

If you look at human genetic populations, particularly several haplogroups prevalent among the first peoples to re-settle Europe after the ice age, and the Middle Eastern peoples they came from, as well as a later Y DNA group associated with the Germanic expansion in prehistory, the low prevalence areas today basically still outline the borders of the Roman Empire at its peak.