Under the Macedonian dynasty (867 to 1057 AD), the Byzantine Empire – heir to the power of Rome and culture of Greece – reached its greatest height of expanse and influence, recovering from a couple centuries of decline. Commencing with Basil I, a number of competent leaders managed victories over the Arabs and the Bulgars, regaining lost territories in Syria and the Balkans. These successes were matched with economic growth, and a flowering of the arts, sciences, and religion. All that thinking about religion by the patriarchs of the land led, it appears, to the “Great Schism” … the break in communion between the Eastern Orthodox and Roman Catholic faiths in 1054.

The Byzantine leaders, commencing in 850, developed the proverbial love-hate relationship with the Viking kingdom of Kiev to the north. The empire quickly became the major trading partner to Kiev, swapping luxury goods for the raw materials so plentiful in the interior north of the Black Sea. After “Christianizing” the Rus, Vladimir of Kiev brought in Byzantine architects and artists to work on all manner of religious projects. Over the next couple centuries, the Kievan and Byzantine imperial families intermarried frequently, and Byzantium made liberal use of the fierce Viking warriors, employing them as mercenaries (notably, in the famed Varangian Guard). But relations were not always so cordial, for several times Viking or Rus raiders attacked Byzantine settlements over the decades.

As different as the East was, its link to trade routes made it vital to the Empire, a significance marked by the establishment of Constantinople as the capital of Rome in 330 AD. Constantine also was the first Roman Emperor to embrace Christianity, and both the geographic move and the religious change seemed to mark a new era in Roman history, one that would eventually lead to the Byzantine Empire. In the hundred years following Constantine, the Western empire suffered wave after wave of invasion from European barbarians, but the East remained relatively stable and prosperous – remember those trade routes to Persia, India, and China! By 476 AD, Rome’s last Western emperor had been deposed, and there was not another, marking for most historians Rome’s fall.

But Rome didn’t really fall. Instead, the Roman Empire was now synonymous with Constantinople, and those people that historians (and we) call “Byzantine” just kept calling themselves “Roman.” The culture of the East was markedly different from the West. The East was largely Greek-speaking (although Byzantine subjects also spoke Coptic in Egypt, Syriac in the Near East, and other languages), and Christianity, while important in the West, was to become absolutely central to Byzantium. The Byzantine Emperor was, for his subjects, God’s representative on Earth and the defender of the Orthodox Christian faith.

If Constantine was the spirit behind Byzantium, Justinian (r. 527-565) was the booster rocket that launched it. It almost didn’t take off, as riots by fans of rival chariot teams (each of which had acquired a political overtone) killed tens of thousands of people, left the city in ashes, and nearly killed the emperor. But worse than the chariot fans were the wars that Justinian had inherited: Byzantium had a hostile Sassanid (Persian) Empire on its borders as well as a series of barbarian kingdoms where the Western Empire used to be: Goths in Rome, Vandals in North Africa. Finally, Justinian inherited an empire with a dizzying array of often-contradictory laws and customs.

These were daunting problems, but Justinian tackled them as best he could. In Constantinople, he appointed a council to review the relevant laws and compile a new “Code of Justinian.” He bought peace with the Persians. In Italy, Justinian retook Rome and parts of the Italian peninsula in a long, drawn-out war with the Gothic kingdoms. In North Africa, Justinian devastated the Vandal kingdom in a war that some historians estimate killed nearly five million. The appearance of the bubonic plague – the first such appearance in European or African history - might also have played a hand. In Justinian’s wake, the Empire was not entirely restored, but it was prosperous, and Rome was in Roman (well, Byzantine) hands again. Justinian’s was to be the greatest extent of the Byzantine Empire in history.

But just when it seemed that Byzantium would reclaim Rome’s old title as the dominant power in the Mediterranean, a new player was to enter the game. About fifty years after Justinian’s death, an Arab prophet – Muhammad – arose. Arab powers, aided by their new faith, Islam, quickly expanded. While a unified Caliphate broke apart shortly after Muhammad’s death, the successor states – the Umayyad and Rashidun Caliphates – quickly took back territory that the Byzantines had taken from the Persians and, significantly, the exceedingly important provinces of Syria and Egypt. At the same time, new invaders from Northern Europe – the Slavs – threatened Byzantine holdings in the Balkans.

Arab forces laid siege to Constantinople for the first (and not last) time in 674. They established naval bases nearby and used these to raid the great city for years. But Constantine IV, the then-Byzantine Emperor, and the city’s massive Theodosian walls were not to be undone so easily. He unleashed a new, devastating weapon upon the sea-borne forces: a mixture of oil and quicklime that burned even when floating on water. This new “Greek fire” drove off the besiegers, at least for now.

The Byzantine Empire at this point was in a sad state. Constant raids, the loss of most of the West to barbarian groups, and the loss of much of its holdings in Africa and the Near East meant that much of the empire stagnated. Remember those important trade routes eastward? This gold now flowed to the Arab states. Byzantine cities emptied out, and Constantinople dwindled. The removal of troops from the Balkans in order to fight the Persians and Arabs gave Slavs – themselves retreating from other invasions from the Central Asian steppe – room to expand, and these new Slavic settlements united into Bulgaria, a sometimes-ally, often-enemy of the Byzantines.

In all of this strife, the Umayyad Caliphate, flush with new conquests in Spain, again saw a chance to take the city, and so a second siege of Constantinople was launched. This time, the Arabs aimed to win, and so secured (they thought) the loyalty of an ambitious general, Leo, who had also secured a military pact with the Bulgarians. Leo declared himself Emperor, but, rather than agree to be a vassal of the Umayyads, he closed the gates to them. With the ever-feared Greek fire, and with ingenious defenses (including a chain set up across a strategic waterway – simple, but enough to stop ships… and render them sitting ducks for more Greek fire). Leo set himself up as a new Roman dynasty, and Arab leaders withdrew – indeed, the failure of this siege likely altered the religious and political face of Eastern Europe and Russia as we know it.

Thus far, the story of the Byzantines may seem to be one of decline. But the subsequent years were to be a time of restoration. Under Basil I and Basil II, the Byzantine empire reformed its military, adopting the professional tagma system and new innovations in cavalry. Byzantine forces repelled Arab invasions – now under the Abbasid Caliphate – across the Aegean coast, and Basil II led a brutal campaign to subjugate the Bulgarians, incorporating their remnants into the Empire in 1018 (they would become independent again over a century later). Even far-off events in Scandinavia were to influence Byzantium, as the Rus plundered down the Volga and the Normans threatened the Mediterranean, although, to be fair, some of these groups would also serve in the Byzantine military.

In the 1100s, Byzantium had its final golden age. Arts and literature thrived, and both city and country saw great gains in infrastructure. Religion was vital to Byzantine life, and it was during the Byzantine Empire that the split between Catholicism, based in old Rome and the former West, and Orthodoxy, based in Byzantium, Greece and the East, happened. Influenced by Muslim ideas and drawing from the Biblical ban on creating “graven images,” Orthodox Christians in the 8th and 9th centuries opposed the creation of icons – images of religious figures, while the Roman pope disagreed (and which led to tensions that would mark the final loss of Byzantine Rome in 756). While the wave of this “iconoclasm” was to abate, it created a split that was to last, as the popes in Rome were no longer appointed by Constantinople. This schism became final in 1054, when the Western (Catholic) church split from the Eastern (Orthodox). The argument this time was not over icons, but over whether the pope in Rome held primacy over other cities’ patriarchs, as well as a host of ritual and theological matters. The split was both a symptom of and the cause for the divergence of Eastern and Western Europe, both in matters of script (Cyrillic vs Latin), language (Greek vs Latin), and custom.

Nowhere was this split more evident than in the disastrous Fourth Crusade in 1204. In 1182, a usurper named Andronikos Komnenos entered Constantinople following the unpopular rule of a Latin-speaking and Western-oriented regent, the Princess Maria of Antioch, whom the populace accused of favoring Catholics over Orthodox. As Maria was deposed, the Orthodox crown began a massacre of Catholic, Latin-speaking citizens of Constantinople. This deepened anti-Byzantine sentiment in the West, and a few decades later, Crusaders supposedly en route to Jerusalem sacked and plundered Constantinople instead, setting up a Catholic crusader state based in the former Rome. Though the Crusaders eventually departed, the East/West split was complete.

And yet another power was to enter the scene – Ottoman Turks, a Central Asian people who had previously been employed as mercenaries by Byzantine and Arab rulers, began to fight for their own kingdom. Byzantium slowly lost ground and, in 1453, the fabled walls of Constantinople fell to Ottoman bombards.

Constantinople is now Istanbul. But its legacy extends as far as the Orthodox Church, into Russia, Greece, Egypt, and Eastern Europe. And the remnants of Constantinople’s famous Theodosian walls remain.