Two crises between AD 330 and 518 helped shape the Greek part of the empire. The first was the invasion by barbarian Huns, Visigoths, and Ostrogoths in the fifth century. Constantinople averted the fate of Rome, which fell to similar onslaughts, by a combination of skillful bribery and a strong army. Thus, as the West was carved into minor kingdoms, the East remained largely intact, and the balance of power in the former Roman Empire moved conclusively to the East.

The second major crisis was religious in nature. In the East, great heresies such as Arianism, Nestorianism, and Monophysitism drew on the rich Greek metaphysical tradition and clashed with the emerging Roman Catholic Church in the fourth and fifth centuries. Among the challengers was an eastern branch of the church with Greek as its language, closely bound to the political world of Constantinople. The Greek Orthodox Christian empire established at this time would bridge Asia and Europe for centuries.

Byzantine Empire