The name Byzantine Empire is derived from the original Greek name for Constantinople; Byzantium. The name is a modern term and would have been alien to its contemporaries. The term Byzantine Empire was invented in 1557, about a century after the fall of Constantinople by German historian Hieronymus Wolf, who introduced a system of Byzantine historiography in his work Corpus Historiae Byzantinae in order to distinguish ancient Roman from medieval Greek history without drawing attention to their ancient predecessors.

Standardization of the term did not occur until the 18th century, when French authors such as Montesquieu began to popularize it. Hieronymus himself was influenced by the rift caused by the 9th century dispute between Romans (Byzantines as we render them today) and Franks, who, under Charlemagne's newly formed empire, and in concert with the Pope, attempted to legitimize their conquests by claiming inheritance of Roman rights in Italy thereby renouncing their eastern neighbours as true Romans.

The Eastern Empire was largely spared the difficulties of the west in the 3rd and 4th centuries (see Crisis of the Third Century), in part because urban culture was better established there and the richer east could more easily afford both to placate invaders with tribute and pay barbarian mercenaries to serve in its armies. Throughout the 5th century, various invading armies overran the western half of the Roman Empire but refrained from ravaging the east. Theodosius II further fortified the walls of Constantinople, leaving the city impenetrable to attacks; it was to be preserved from foreign conquest until 1204. To spare the Eastern Roman Empire from the invasion of the Huns of Attila, Theodosius gave them subsidies, said to be 300kg (700lbs) of gold. Moreover, he favored merchants living in Constantinople who traded with the barbarians.

His successor, Marcian, refused to continue to pay this exorbitant sum. However, Attila had already diverted his attention to the Western Roman Empire. After he died in 453, the Hunnic Empire collapsed and Constantinople breathed again, even starting a profitable relationship with the remaining Huns, who would eventually fight as mercenaries in Byzantine armies.

After the fall of Attila, the true chief in Constantinople was the Alan general Aspar. Leo I managed to free himself from the influence of the barbarian chief favouring the rise of the Isaurians, a semi-barbarian tribe living in Roman territory, in southern Anatolia. Aspar and his son Ardabur were murdered in a riot in 471, and henceforth, Constantinople was freed from the influence of barbarian leaders for centuries.

The origins of Byzantium are shrouded in legend. The traditional legend has it that Byzantium was founded by Byzas from Megara when he sailed northeast across the Aegean Sea. Byzas had consulted the Oracle at Delphi to know where to make his new city.

The Oracle told him to found it "opposite the blind." At the time, he did not know what this meant. But when he came upon the Bosporus he realized what it meant: on the Asiatic shore was a Greek city, Chalcedon. It was they who must have been blind because they had not seen that obviously superior land was just a half mile away on the other side of the Bosporus. Byzas founded his city here in this "superior" land and named it Byzantion after himself. It was mainly a trading city due to its strategic location at the Black Sea's only entrance. Byzantion later conquered Chalcedon, across the Bosporus.

After siding with Pescennius Niger against the victorious Septimius Severus, the city was besieged by Roman forces and suffered extensive damage in CE 196. Byzantium was rebuilt by Septimius Severus, now emperor, and quickly regained its previous prosperity. The location of Byzantium attracted Roman Emperor Constantine I who, in CE 330, refounded it as Nova Roma. After his death the city was called Constantinople, It was the capital of the Eastern Roman Empire, or Byzantine Empire as it was called during and after Emperor Justinian's reign.

This combination of imperialism and location would affect Constantinople's role as the crossing point between two continents: Europe and Asia. It was a commercial, cultural, and diplomatic magnet. At a strategic position, Constantinople could control the route between Asia and Europe, as well as the passage from the Mediterranean Sea to the Black Sea.

On May 29, 1453, the city fell to the Ottoman Turks, and, once again, became the capital of another powerful empire, The Ottoman Empire.