Complex sentence: The descendants of populations of Albanian origin who settled in Greece during the Middle Ages are the Arvanites, who have fully assimilated into the Greek nation and self-identify as Greeks, although they still maintain their distinct dialect of Tosk Albanian known as Arvanitika.
Split into simpler sentences: The descendants of populations of Albanian origin who settled in Greece during the Middle Ages are the Arvanites, who have been fully assimilated into the Greek nation and self-identify as Greeks. Today, they still maintain their distinct dialect of Tosk Albanian, known as Arvanitika.