History of Europe
In 395 Theodosius I, who had made Christianity the official religion of the Roman Empire, would be the last emperor to preside over a united Roman Empire. The empire was split into two halves: the Western Roman Empire centred in Ravenna, and the Eastern Roman Empire (later to be referred to as the Byzantine Empire) centred in Constantinople. The Roman Empire was repeatedly attacked by Hunnic, Germanic, Slavic and other “barbarian” tribes (see: Migration Period), and in 476 finally the Western part fell to the Heruli chieftain Odoacer.
Roman emperor
After the fall of Constantinople, Thomas Palaiologos, brother of Constantine XI, was elected emperor and tried to organize the remaining forces. His rule came to an end after the fall of the last major Byzantine city, Corinth. He then moved in Italy and continued to be recognized as Eastern emperor by the Christian powers.