Eastern Roman Empire
From Tardis Wiki, the free Doctor Who reference
The Byzantine Empire, also known as the Eastern Roman Empire, was a human empire which split off from the original Roman Empire. Benny told Ace that the city of Byzantium was renamed Constantinople after Emperor Constantine I. It became "the capital of the Eastern Roman Empire until the 15th century, when it was captured by the Turks". (PROSE: Shadowmind)
