Byzantium, or the City of Constantine - Constantinople, the "New Rome" of the Eastern Empire, was destined to become from the early fourth century AD the capital of the Byzantine or Medieval Greek Empire, which was meant to play a dominant role in the historical development of the peoples and nations of the southeastern Mediterranean basin for about eleven and a half centuries until, shortly after the mid-fifteenth century, another great power, the Ottoman Turks, coming from the East, replaced the Byzantine Empire in this critical era.

Throughout its long duration, the Byzantine Empire managed to survive through countless external threats from the West, the North, and the East amidst many internal upheavals. Simultaneously, it succeeded in creating a great self-sufficient culture and civilization, with remarkable achievements in literature, sciences, and the arts.

The key features of this unique civilization were not only the ancient Greek and Hellenistic heritage and the Greek Orthodox Christian tradition but also the penetrating social, institutional, economic, and cultural changes and reforms that led to the gradual transformation of the late Roman state into a clearly medieval Greek state.

The beginning of the Byzantine Empire inaugurates the history of medieval Hellenism, while its final downfall coincides with the dawn of modern Hellenism through the difficult centuries of Ottoman rule.