"The origins of the great civilization known as the Byzantine Empire can be traced to 330 A.D., when the Roman emperor Constantine I dedicated a “new Rome” on the site of the ancient Greek colony of Byzantium. Though the western half of the Roman Empire crumbled and fell in 476, the eastern half survived for 1,000 more years, spawning a rich tradition of art, literature and learning and serving as a military buffer between the states of Europe and the threat of invasion from Asia. The Byzantine Empire finally fell in 1453, after an Ottoman army stormed Constantinople during the reign of Constantine XI."
"Byzantine Empire was the successor of the Roman Empire in the Greek-speaking, eastern part of theMediterranean. Christian in nature, it was perennially at war with the Muslims, Flourishing during the reign of the Macedonian emperors, its demise was the consequence of attacks by Seljuk Turks, Crusaders, and Ottoman Turks."
"Byzantium was the name of a small, but important town at the Bosphorus, the strait which connects the Sea of Marmara and the Aegean to the Black Sea, and separates the continents of Europe and Asia. In Greek times the town was at the frontier between the Greek and the Persian world. In the fourth century BCE,Alexander the Great made both worlds part of hishellenistic universe, and later Byzantium became a town of growing importance within the RomanEmpire."
"By the third century CE, the Romans had many thousands of miles of border to defend. Growing pressure caused a crisis, especially in the Danube/Balkan area, where the Goths violated the borders. In the East, the Sasanian Persians transgressed the frontiers along the Euphrates and Tigris. The emperor Constantinethe Great (reign 306-337 CE) was one of the first to realize the impossibility of managing the empire's problems from distant Rome."
"The Byzantine Empire made great contributions to civilization: Greek
language and learning were preserved for posterity; the Roman imperial system
was continued and Roman law codified; the Greek Orthodox church converted some
Slavic peoples and fostered the development of a splendid new art dedicated to
the glorification of the Christian religion. Situated at the crossroads of
east and west, Constantinople acted as the disseminator of culture for all
peoples who came in contact with the empire. Called with justification "The
City," this rich and turbulent metropolis was to the early Middle Ages what
Athens and Rome had been to classical times. By the time the empire collapsed
in 1453, its religious mission and political concepts had borne fruit among
the Slavic peoples of eastern Europe and especially among the Russians. The
latter were to lay claim to the Byzantine tradition and to call Moscow the
"The eastern half of the Roman Empire proved less vulnerable to external attack, thanks in part to its geographic location. With Constantinople located on a strait, it was extremely difficult to breach the capital’s defenses; in addition, the eastern empire had a much shorter common frontier with Europe. It also benefited greatly from a stronger administrative center and internal political stability, as well as great wealth compared with other states of the early medieval period. The eastern emperors were able to exert more control over the empire’s economic resources and more effectively muster sufficient manpower to combat invasion. As a result of these advantages, the Eastern Roman Empire–variously known as the Byzantine Empire or Byzantium–was able to survive for centuries after the fall of Rome."
"Byzantium is the name given to both the state and the culture of the Eastern Roman Empire in the middle ages. Both the state and the inhabitants always called themselves Roman, as did most of their neighbors. Western Europeans, who had their own Roman Empire called them Orientals or Greeks, and later following the example of the great French scholar DuCange, Byzantines after the former name of the Empire's capital city, Constantinople."
SURVIVAL OF THE BYZANTINE EMPIRE
"The seventh to ninth centuries are generally accounted a low point of Byzantine history. Little literature - even saints' lives - survives, and even less art. The period is studied above all for the history of the struggle over icons. This Iconoclastic Controversy bears witness to a continued intellectual vitality, and the emergence of one of history's most sophisticated analyses of the nature and function of art. Under the Macedonian Dynasty [867-1056], Byzantium's political power reached its apogee as former territories were incorporated in the Empire, and an element of multi-ethnicity was restored. This period is also significant as the time in which Byzantine culture was spread among the Slavs and other Balkan peoples. Following massive Turkish attacks in the late eleventh century, the Empire was able to maintain a lesser but still significant political and military power under the Komnenian Dynasty: the cost was a social transformation which exalted a powerful military aristocracy, and gradually enserfed the previously free peasantry. In 1204, internal Byzantine politics and the resurgent West, effectively ended the imperial pretensions of the Byzantine state. The Fourth Crusade  succeeded in conquering Constantinople and making it a Latin principality for half a century. The Greek political leadership, under the Palaiologan Dynastyregained Constantinople in 1261, but the "empire" was just one state among many in the area for the final 200 years of its existence. Strangely, this period was among the most culturally productive, in art, in theology, and in literature."
THE BYZANTINE EMPIRE UNDER JUSTINIAN
Throughout the 5th century various invasions conquered the western half of the empire, but at best could only demand tribute from the eastern half. Theodosius II enchanced the walls of Constantinople, leaving the city impenetrable to attacks: it was to be preserved from foreign conquest until 1204. To spare his part of Empire the invasion of the Huns of Attila, Theodosius gave them subsidies of gold: in this way he favoured those merchants living in Constantinople who traded with the barbarians. His successor Marcian refused to continue to pay the great sum, but Attila had already diverted his attention to the Western Empire and died in 453.
This served as a precedent for Wolf who was motivated, at least partly, to re-interpret Roman history in different terms. Nevertheless, this was not intended in a demeaning manner since he ascribed his changes to historiography and not history itself.
Under Theodosius I (r. 379-395), Christianity became the Empire's official state religion and others such as Roman polytheism were proscribed. And finally, under the reign of Heraclius (r. 610-641), the Empire's military and administration were restructured and adopted Greek for official use instead of Latin. In summation, Byzantium is distinguished from ancient Rome proper insofar as it was oriented towards Greek rather than Latin culture, and characterised by Orthodox Christianity rather than Roman polytheism.
The final centuries of the Empire exhibited a general trend of decline. It struggled to recover during the 12th century, but was delivered a mortal blow during the Fourth Crusade, when Constantinople was sacked and the Empire dissolved and divided into competing Byzantine Greek and Latin realms. Despite the eventual recovery of Constantinople and re-establishment of the Empire in 1261, Byzantium remained only one of several small rival states in the area for the final two centuries of its existence. This volatile period led to its progressive annexation by the Ottomans over the 15th century and the Fall of Constantinople in 1453.
BYZANTIUM AND THE CRUSADERS
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.
In 468 an attempt by Leo I to conquer again Africa from the Vandals had failed mercilessly, showing how feeble were the military capabilities of the Eastern Empire. At that time the Western Roman Empire was already restricted to the sole Italy: Britain had fallen to Angles and Saxons, Spain to Visigoths, Africa to Vandals and Gaul to Franks.
Anastasius revealed himself to be an energic reformer and able administrator. He perfected Constantine I's coin system by definitively setting the weight of the copper follis, the coin used in most everyday transactions. He also reformed the taxation system: at his death the State Treasury contained the enormous sum of 320,000 pounds of gold.
fThe 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.