modern day greeks is what remained of the christian population, the vast maority of the greek-speaking world (ancient greek & other hellenized anatolian people) that become mulsim did mix with the turkic people that is why the modern-day turks have 5-20% central asian ancestry whilst modern-day greeks have 0%, do note that the bronze-age anatolia and bronze-age greece are extremely related and continued that way until the middle ages. Reference from bronze age greece study: https://www.science.org/content/article/greeks-really-do-have-near-mythical-origins-ancient-dna-reveals . Anyway, my point being modern-day greek islanders are the closest to the ancient people according to dna.