Ilẹ̀ọbalúayé Rómù Apáìlàoòrùn
The Byzantine Empire (or Byzantium) was the Eastern Roman Empire during Late Antiquity and the Middle Ages, centered on the capital of Constantinople. Known simply as the "Roman Empire" (Greek: , "Basileia Rhōmaiōn"; ) or Romania () to its inhabitants and neighbours, it was the direct continuation of the Ancient Roman State and maintained Roman state traditions. Byzantium is today distinguished from ancient Rome proper insofar as it was oriented towards Greek culture, characterised by Christianity rather than Roman polytheism, and was predominantly Greek-speaking rather than Latin-speaking.
As the distinction between "Roman Empire" and "Byzantine Empire" is largely a modern convention, it is not possible to assign a date of separation; however, important points are the Roman Empire's administrative division into western and eastern halves in 285 by Emperor Diocletian (r. 284–305), and Emperor Constantine I's (r. 306–337) decision in 324 to transfer the capital from Nicomedia (in Asia Minor) to Byzantium on the Bosphorus, which became Constantinople, "City of Constantine" (alternatively "New Rome"). The Roman Empire was finally divided in 395 AD after the death of Emperor Theodosius I (r. 379–395), thus this date is also very important if the Byzantine Empire (or Eastern Roman Empire) is looked upon as completely separated from the West. The transition to Byzantine history "proper" finally begins during the reign of Emperor Heraclius (r. 610–641), since Heraclius effectively established a new state after reforming the army and administration by introducing themes and by changing the official language of the Empire from Latin to Greek.
As the Western Roman Empire decayed and fragmented into numerous separate kingdoms, the Byzantine Empire continued to survive, existing for more than a thousand years from its genesis in the 4th century until the Fall of Constantinople in 1453. During most of its existence, it remained one of the most powerful economic, cultural, and military forces in Europe, despite setbacks and territorial losses, especially during the Roman–Persian and Byzantine–Arab Wars. The Empire recovered during the Macedonian dynasty, rising again to become a preeminent power in the Eastern Mediterranean by the late 10th century, rivaling the Fatimid Caliphate.
After 1071, however, much of Asia Minor, the Empire's heartland, was lost to the Seljuk Turks. The Komnenian restoration regained some ground and briefly reestablished dominance in the 12th century, but following the death of Emperor Andronikos I Komnenos (r. 1183–1185) and the end of the Komnenos dynasty in the late 12th century the Empire declined again. The Empire received a mortal blow in 1204 from the Fourth Crusade, when it was dissolved and divided into competing Byzantine Greek and Latin realms.
Despite the eventual recovery of Constantinople and re-establishment of the Empire in 1261, under the Palaiologan emperors, Byzantium remained only one of many rival states in the area for the final two centuries of its existence. However, this period was the most culturally productive time in the Empire. Successive civil wars in the 14th century further sapped the Empire's strength, and most of its remaining territories were lost in the Byzantine–Ottoman Wars, which culminated in the Fall of Constantinople and the conquest of remaining territories by the Ottoman Empire in the 15th century.