southern italy was under spanish kingdom from 1300 to 1700 long after the greeks
anyway most of people didn't mix with greeks or spanish since who ruled in the fact were local barons it's a mixed places like tons of other in the world not more not less
the ridiculous fact it's find some etnich roots after 500 or 1.000 years, it's like we trace our roots in africa were the human race probably was born lol