It only makes sense that there would be an intermingling of
people when the two large races rub to together so to speak.
Look at an Ethiopian, many have very ‘Caucasian’ features.
They live between the two large races of people.
I guess the thing that they are look for is are they Roman decent? Do they have a haplogroup of just ancient Romans?
Whole populations were removed hundreds and thousands of mile from their birthplace.
If you read Gibbon, it is amazing how often this took place. Extremely remote and numerous groups were moved around on a scale and with a frequency that is difficult to imagine, yet is was customary.
Don't forget, slaves represented wealth and hardly any defeated populations were left in place or in tact. And of course, DNA moved around with them.
One author said that slavery became SO necessary because in the ancient world, there was not enough gold available for the valuation of commodities... slaves were currency.