Byzantinism, a not sufficiently explored field, is still today a fundament of the pejorative explanation of the terms “Balkanization” and “Balkanism”. Byzantinism, the Hellenic one, actually represents the whole idea for the Balkans; the idea of how, due to the hegemonization of an ethnic identity, an empire that persisted for about a millennium could collapse. The idea of this text is to show the connection between Byzantinism and Balkanism and by using synthesis and comparative analysis to prove the thesis that: The hegemonization of the Byzantine-Greek identity in the past contributed to the birth of today's Balkan nationalism - Balkanism. In this text, the author analyses the appearance of Byzantium as a par excellence addition to ancient Hellenism, especially its conversion into hegemonic Hellenism, which was intended to submerge and assimilate all the other non-Greek identities in Byzantium. In fact, the author will prove that Byzantinism, which is a product of Hellenism, is the source of Balkanism, which itself leads to the idea that the fundament of today's Balkan nationalism, that is, Balkanism, is nothing but the hegemonic Hellenism during the Byzantine Empire.