Since the nineteenth century, Greece and Albania have been separate countries, but for about twenty-two centuries they belonged to the same state in its various forms. The ancient Greeks and Illyrians were Indo-European tribes who intermarried with pre-Hellenic populations after arriving in the Balkans about four thousand years ago. Multiple migration events occurred to and from one another's lands; in ancient years Greek cities like Corinth established colonies on the Illyrian coast, while in the Middle Ages Albanian speakers (known as Arvanites) migrated across Greece. Hundreds of years later, another five hundred thousand Albanian speakers had immigrated to Greece after 1985. The data show that Greeks and Albanians have a long-term kinship, but this is obscured by linguistic and religious differences. Understanding this common past may strengthen contemporary political relationships.