The Byzantine Empire: How Rome's Eastern Half Endured a Millennium

A narrative history of the empire that called itself Roman, from Constantine's new capital through Justinian, Iconoclasm and 1204 to its last centuries, with the debates along the way.

Avevide · Last reviewed October 24, 2026 · 8 min read

The people we call Byzantines never used the word. As the Metropolitan Museum of Art's overview of the empire puts it, the state ruled from Constantinople "would come to be called Byzantium by modern historians," while its own citizens called themselves Rhomaioi, Romans, and saw themselves as heirs of the ancient Roman Empire.

They had a point. When Rome itself was sacked in the fifth century, the eastern half of the empire carried on, Christian and increasingly Greek-speaking, for roughly another thousand years. The Met's essay notes that the empire endured "more than 1,100 years after its first founding" before its last lands fell to the Ottomans in the mid-fifteenth century.

This deep dive follows that long life in broad stages: the founding of a new capital, Justinian's attempt to restore the old empire, the losses and reinventions of the seventh and eighth centuries, a medieval revival, the catastrophe of 1204, and a small but culturally vibrant late empire.

A new Rome on the Bosphorus

The story begins with Constantine the Great, the first Christian ruler of the Roman Empire. The Met's essays date his refounding of the old port of Byzantion to 324 and his transfer of the imperial capital there to 330. He renamed it Constantinople, "the city of Constantine," and it was also called the New Rome.

The site mattered. The city sat on the easternmost edge of Europe at a major intersection of east-west trade. Christianity replaced the old gods as the official religion in the late 300s, and Christian monasticism spread from Egypt to all parts of the empire.

Meanwhile the west unraveled. Rome was sacked by the Goths in 410 and by the Vandals in 455. In the east, according to the Met, an educated elite used Roman law and Greek and Roman culture to run "a highly organized government centered on the court and its great cities." That administrative continuity is one reason the eastern empire survived when the western one did not.

Justinian's gamble

Justinian I, who reigned from 527 to 565, tried to put the old empire back together. The Met describes him as drawing on administrators from outside the aristocracy and pronouncing that the emperor's will was law. His modest origins, his choice of advisers, and his authoritarian style all fed lasting tensions with the nobility.

Those tensions exploded in the Nika Riot in the Hippodrome of Constantinople in January 532. Rioters burned key buildings, including the old cathedral of Hagia Sophia. The court historian Procopius, in H. B. Dewing's translation of his History of the Wars, says that when the revolt was crushed "there perished among the populace on that day more than thirty thousand." That number is Procopius's own, and ancient casualty figures are rarely precise, but it conveys the scale of the bloodshed.

Justinian turned the destruction into an opportunity. Between 532 and 537, the architects Anthemius of Tralles and Isidorus of Miletus rebuilt Hagia Sophia with a vast dome resting on pendentives. Procopius, in Aubrey Stewart's 1888 translation of The Buildings, wrote that the dome "does not appear to rest upon a solid foundation, but to cover the place beneath as though it were suspended from heaven by the fabled golden chain."

Abroad, Justinian launched campaigns to recover Italy and North Africa from Germanic rulers. By his death in 565, the Met notes, the empire bordered nearly the entire Mediterranean, a size it would never reach again. At home, his legal reforms were codified in the Corpus Juris Civilis, which still forms part of the foundation of Western law.

The costs were heavy. Procopius records a terrible plague in the early 540s, "a pestilence, by which the whole human race came near to being annihilated," in Dewing's rendering. And the gains did not last: many of the Italian provinces fell to the Lombards in the late 500s.

Loss and reinvention in the seventh and eighth centuries

The 600s brought disaster. Persian and then Arab invasions, in the Met's words, "devastated much of Byzantium's eastern territories," and Egypt and North Africa were lost to the Arab conquest in the seventh century.

The empire adapted rather than collapsed. From the seventh to the twelfth centuries, the Met explains, a system of military governorship over administrative districts called themes provided government for distant territories. Defense and administration were fused at the local level.

The eighth century then brought a crisis of belief. Iconoclasm, meaning "image breaking," was a theological and political struggle that ran roughly from 726 to 787 and again from 815 to 843. Imperial legislation barred figural religious images and promoted the cross instead, and archaeological evidence suggests icons were destroyed or plastered over in places such as Constantinople and Nicaea. Why it happened is still debated. The Met's essay says the immediate causes "have been hotly contested by scholars," with suggestions ranging from the rise of Islam to an emperor's desire to take over religious authority and funds.

The Middle Byzantine revival, 843 to 1204

The restoration of icons in 843 opened what the Met calls a second flowering of the empire. Greek became the official language of state and church. Christianity spread from Constantinople into the Slavic lands to the north, which is why Orthodox Christianity shaped much of Eastern Europe. Campaigns to recover territory lost to Arab armies, including Syria and Crete, met with some success. The first great monasteries were founded on Mount Athos, and manuscript production reached a peak.

The danger came from a new direction. The Library of Congress's country study of Turkey describes how, in 1071, the Seljuk sultan Alp Arslan "routed the Byzantine army at Manzikert near Lake Van," opening Anatolia to Turkish conquest. Within ten years, the Seljuks controlled most of it, and land the empire had held for centuries became a Turkish frontier.

The Seljuk advance in turn, as the same country study puts it, stimulated a response from Latin Europe in the form of the First Crusade. A counteroffensive launched in 1097 by the Byzantine emperor with crusader help restored Byzantine rule in the western third of Anatolia. But relations with the western knights soured with each expedition.

1204: the sack by fellow Christians

The Fourth Crusade set out in 1202 with Egypt as its goal. According to the Met's essay on the Crusades, the crusaders took sides in a Byzantine dynastic dispute and then turned on Constantinople to collect an enormous sum that had been promised for their support. In 1204 they sacked the city and divided its treasures among the Venetians, the French, and others; much of the Venetian share remains in the Treasury of San Marco in Venice.

One of the crusade's leaders left a frank record. Geoffrey of Villehardouin, in Frank T. Marzials's 1908 translation of his chronicle, testified that "never, since the world was created, had so much booty been won in any city."

The crusaders crowned Baldwin of Flanders as emperor of a new Latin Empire of Constantinople. Byzantine rulers in exile set up rival states at Arta in Epirus, at Trebizond on the Black Sea, and at Nicaea in western Asia Minor. It was Nicaea that retook Constantinople in 1261 under a new dynasty, the Palaiologoi. The Met judges that the Latin occupation caused "major political fragmentation" and the dislocation of the empire's nobility.

The late empire: a small state with a long shadow

The restored empire was much smaller. The Turkey country study describes it as an essentially Balkan state reduced to Thrace and northwestern Anatolia, while the Met places its focus on Constantinople, northern and central Greece, and the Peloponnese. The separate Byzantine Empire of Trebizond competed with it.

Yet culture flourished. The Met notes, as a "surprising contrast" to the military and political situation, that patrons at all social levels built and restored churches and monasteries, and that the Palaiologan emperors repaired and embellished Hagia Sophia. Icons in more modest materials, such as miniature mosaics of colored stone and glass, became popular as funds shrank and lesser metals replaced gold and silver.

The end came in stages: Constantinople fell to the Ottoman Turks in 1453, and the remaining Byzantine centers at Mistra and Trebizond within a few years. Even then, in the Met's words, Byzantium "set a standard for luxury, beauty, and learning that inspired the Latin West and the Islamic East."

Why did it last so long?

There is no single answer, and historians weigh the factors differently. The sources used here point to several that recur. The capital's position at a crossroads of trade kept the center alive through repeated losses at the edges. Roman law and a professional administration gave continuity across dynasties. The empire repeatedly reorganized itself, as with the theme system, rather than trying to hold every province on the old terms. And its church and culture extended its influence well beyond its shrinking borders.

It is also worth remembering that the "decline" seen with hindsight was not a straight line. The empire lost and regained territory many times, and art and architecture flourished for long stretches of its last two centuries.

Key takeaways

"Byzantine" is a modern label; the empire's people called themselves Romans and saw their state as the Roman Empire's continuation.
Justinian's sixth-century reconquests and building program were spectacular but costly, and much of the territory was soon lost.
The empire survived the seventh-century Arab conquests by reorganizing, including through military districts called themes.
Scholars still debate the causes of Iconoclasm, the eighth- and ninth-century struggle over religious images.
The crusader sack of 1204 shattered the state; the empire restored in 1261 was small but culturally vital until 1453.

Sources

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