The Byzantine Empire or Eastern Roman Empire, was the Roman Empire during the Middle Ages, centered on the capital of Constantinople, and ruled by Byzantine emperors. It was called the Roman Empire, and also as Romania (Greek: Ῥωμανία, Rhōmanía), by its inhabitants and its neighbours. As the distinction between "Roman Empire" and "Byzantine Empire" is purely a modern convention, it is not possible to assign a date of separation, but an important point is the Emperor Constantine I's transfer in 324 of the capital from Nicomedia (in Anatolia) to Byzantium on the Bosphorus, which became Constantinople (alternatively "New Rome").[n 1]
The Empire 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 the pre-eminent power in the Eastern Mediterranean by the late tenth century. 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 re-established dominance in the twelfth century, but declined again under their successors. The Empire received a mortal blow in 1204 by 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, successive civil wars in the fourteenth century further sapped the Empire's strength. Most of its remaining territory was lost in the Byzantine–Ottoman Wars, culminating in the Fall of Constantinople and its remaining territories to the Muslim Ottoman Turks in the fifteenth century.
The designation of the Empire as "Byzantine" began in Western Europe in 1557, when German historian Hieronymus Wolf published his work Corpus Historiæ Byzantinæ, a collection of Byzantine sources. "Byzantine" itself comes from "Byzantium", the name of the city of Constantinople before it became the capital of Constantine. This older name of the city would rarely be used from this point onward except in historical or poetic contexts. The publication in 1648 of the Byzantine du Louvre (Corpus Scriptorum Historiæ Byzantinæ), and in 1680 of Du Cange's Historia Byzantina further popularized the use of Byzantine among French authors, such as Montesquieu.[3] It was not until the nineteenth century, however, with the birth of modern Greece, that the term "Byzantine" came into general use in the Western world. Before this time Greek had been used for the Empire and its descendants within the Ottoman Empire.
The Empire was known to its inhabitants as the Roman Empire, the Empire of the Romans (Latin: Imperium Romanum, Imperium Romanorum, Greek: Βασιλεία τῶν Ῥωμαίων, Basileía tôn Rhōmaíōn), Romania[n 2] (Ῥωμανία, Rhōmanía), Roman Republic (Latin: Res Publica Romana, Greek: πολιτεία Ῥωμαίων, politeίa Rhōmaíōn),[5] and also as Rhōmaís (Ῥωμαΐς).[6]
Although Byzantium had a multi-ethnic character during most of its history,[7] it preserved Romano-Hellenistic traditions[8] and was usually known to most of its western and northern contemporaries as the Empire of the Greeks[n 3] due to the increasing predominance of the Greek element.[9] The use of the term Empire of the Greeks (Latin: Imperium Graecorum) in the West to refer to the Eastern Roman Empire also implied a rejection of the empire's claim to be the Roman Empire.[10] The claims of the Eastern Roman Empire to Roman inheritance had been actively contested in the West at the time of the Roman Empress Irene of Athens, due to the coronation of Charlemagne as Holy Roman Emperor year 800, by Pope Leo III, who needing help against enemies in Rome, saw the throne of the Roman Empire as vacant (lacking a male occupant). Whenever the Popes or the rulers of the West made use of the name Roman to refer to the eastern Roman Emperors, they preferred the term Imperator Romaniæ instead of Imperator Romanorum, a title that Westerners maintained applied only to Charlemagne and his successors.[11]
By contrast, in the Persian, Islamic, and Slavic worlds, the Empire's Roman identity was generally accepted. In the Islamic world it was known primarily as روم (Rûm "Rome").[12][13]
In modern historical atlases, the Empire is usually called the Eastern Roman Empire in maps depicting the empire during the period AD 395 to AD 610, after the new emperor Heraclius changed the official language from Latin to Greek (already the language known by the great majority of the population); in maps depicting the Empire after AD 610, the term Byzantine Empire usually appears.