HistoryConstantine the Great took power in the Battle of Milvian Bridge from the Western Roman emperor Maxentius and proceeded to set the new capital of the Roman Empire at the former Greek city of Byzantium, which became known as "Constantinople". The city flourished as Constantine gave rise to a Greco-Roman blend of an empire, and after his death in 337 AD, the empire split with the Roman Empire for the sake of easier management.
With Constantinople as the capital of the Eastern Roman Empire, the nation controlled present-day Turkey, Syria, Israel, Lebanon, Syria, Jordan, Egypt, and parts of Iraq as of 363 AD. The empire waged war against the neighboring Sassanid dynasty of Persia, the Zoroastrians who had killed Western Roman emperor Julian the Apostate in 363 AD in battle. The Eastern Roman emperor Theodosius I dealt with their threat by assisting rebellious noble Kuru I of Persia in taking control, and Persia became a puppet of the Byzantines. Loyal Sassanid strongholds in Armenia and Media fell to Byzantine hands, and the Sassanids were exiled to central Russia.While these wars against the Persians were being waged, the Byzantines also fought against rebels. Many revolts occurred, with uprisings in Sinope and Philadelphaea becoming the most common. The cities of Sinope, Jerusalem, Philadelphaea, Arsakia, and Campus Quadi all rebelled at separate times, and all of them were crushed, and the populace exterminated by crucification as an example to the people. Also, the Byzantine emperors had a strict policy of anti-Paganism, which later spread to anti-Arianism and anti-Zoroastrianism. Temples of these religions were destroyed and replaced by Christian churches, and by 401 AD Christianity was the dominant European religion.
In the late 4th century, the Western Roman Empire was toppled by internal revolts, so in 401 AD Theodosius dispatched General Luca Flavius to take control of Italy. Flavius and his army were only around 30% Roman; the vast majority were Illyrian or northern Italian troops hired as mercenaries. He captured Ravenna in 401 AD and proceeded to take Rome in 402 AD, and by then, Theodosius had died; Luca became the new Augustus. Ruling over Rome and Constantinople, he restored a pan-Roman empire, but died in 406 AD while preparing to conquer the island rebels of Sicily.
Succeeding emperors conquered Sicily and Sardinia from the Western Roman rebels and repelled the invasion of the Slavs from 410 to 428 AD, and the Alemanni invasion was halted in the 440s. Combatting outsiders, the Eastern Roman Empire went on the defensive by 453, as they had controlled most of the former Roman Empire and needed to consolidate. The Western Roman emperors ruled from Britannia, but had no control over their former European lands, ruled from Constantinople instead of Rome.
In 476 AD, the Western Roman Empire finally fell to the invaders. The Eastern Roman Empire, now the only Roman nation left, became the Byzantine Empire, representing the Roman Empire for almost one thousand more years until they were conquered by the Ottoman Empire, their power having already been broken by the successor kingdoms of the barbarians.