A little research on the history of Greece during the Byzantine Empire will indicate that the country now known as Greece was largely abandoned by “Greeks,” and resettled by Slavs. They were later reconquered by the Empire and Hellenized.
But it’s pretty debatable whether there’s much more genetic correspondence between the ancient Athenians and the modern Greeks than anybody else in the general vicinity.
I’m tempted to push the “abuse” key!! What kind of comment is that to post on this type of thread?! ;)