The Byzantine Empire was a continuation of the Roman Empire in the
eastern Mediterranean area. Its name comes from Byzantium,
the ancient name of Constantinople so named
after Constantine made it the capital of the Roman Empire in AD 330.
It is also called the East Roman, or Greek Empire because its official language was not Latin but Greek. Some historians date the beginning of the empire AD 395 when the Roman Empire was split into Eastern and Western parts. The Byzantine Empire ended in 1453, when Constantinople fell to the Turks.
That date also marks the end of the Middle Ages.