The Byzantine Empire was a result of the 2 division of the former All-Roman Empire in 395 to the two rulers Honorius and Arcadius, both sons of the Roman ruler Theodosius.
But while the Western Roman Empire slowly countered its downfall, the Eastern Roman Empire could survive for some years. After the downfall of West Rome at the end of the fifth century and its disintegration, the Eastern Roman Empire was able to hold its ground against the internal power struggles. In the 6th century, Emperor Justinian, together with the two Eastern Roman generals Belisarius and Narses, began to incorporate the lost western territories into the Roman Empire. In these campaigns, large parts of Italy, North Africa and southern Spain were conquered.
But already under his successor Justin II, the empire lost end of the 6th century parts of Italy to the Lombards and the advancing Slavs took areas on the beam. At the beginning of the 7th century, another war with the Sassanid Persians was added, as a result of which the empire lost parts of its eastern territory, as well as Egypt and Syria, and the Persians came as far as the capital, Constantinople. In the year 610 the reign of Phokas brought the turnaround. He led several campaigns against the Persians, could push them back to their own area and won a decisive victory in 627 in the battle of Nineveh. Through the burgeoning internal infighting within the Persian Empire, a peace treaty was negotiated, which also included the return of the North African territories and Syria. The areas in the Balkans, however, could not be reconquered due to the exhausting war against the Persians.
However, the Reich did not have a long time of peace. Already at the beginning of 630, the Muslim-influenced Arabs spread to more and more areas in the Middle East. Once again the eastern territories were lost, in the Battle of Jarmuk on August 20, 636, the already weakened Eastern Roman army suffered a heavy defeat, and the entire southeast of the empire, including Syria, Egypt, and Palestine, was completely lost until 642. 698 lost the rest of Africa and Carthage.
During this period until the 8th century, the feeling, culture and structure of the empire changed so profoundly that the result was a transformation from the former Eastern Roman Empire into the Byzantine Empire. By the end of the eighth century, moreover, military actions were almost exclusively of a defensive character and were intended to protect the Reich territories from attacking Arabs.
Until the 11th century, the largest part of the Reich territory could be held through restructuring and determined fighting. However, in the 11th century, a period of heavy defeats began and more areas were lost. Thus, the Normans conquered 1071 southern Italy and in the same year almost all the rest of the area in Asia Minor fell to the Seljuk Turks. At the end of the 11th century, a request for help from the Byzantine ruler Alexios I Komnenos led to Western Western aid to the Muslims for the first crusade. Although the European rulers sent their knight armies in the Middle East, a liberation and support for the Byzantine Empire was not planned and so Alexios I Komnenos remained on his own.
In the 12th century, internal crises shook the empire, and Alexius IV attempted to use the Crusaders for his claim to the throne, conquering it after the pay failed. Constantinople and plundered the city. The Byzantine Empire then disintegrated into 3 small states, the Empire of Nicaea, the despot of Epirus and the Empire of Trebizond. It was not until the reign of Emperor Michael VIII in 1261 that Constantinople was reconquered and some of the empire was reconciled. In the 14th century, the Ottomans managed to take more and more areas in the Balkans towards Europe and under duress to annex the Bulgarian rulers as vassals. Under pressure, the shrunken Byzantine Empire had to submit to the rule of the Ottoman sultan. Only with the victory of Tamerlane in Angora in 1402 could the supremacy of the Ottomans be broken. But due to the many lost areas and military defeats, the Byzantine remnant was barely survivable. By the end of 1450, the alliance of European states was still able to win some victories over the Ottomans, but the liberation of the Byzantine Empire was disputed, which the Ottomans used to besiege Constantinople in April 1453.
After almost two months of siege, the capital of the empire fell to Mehmed II on May 29, 1453. The last Byzantine emperor Constantine XI. could not withstand the siege with his approximately 5,000 soldiers and died during the fighting for the city.
After the conquest of Constantinople and the downfall of the Byzantine Empire, the last small states that emerged from the former empire were conquered. Thus Despotat Morea fell in 1460, the Empire of Trebizond in 1461 and the Principality of Theodoro in 1475. Only Monemvasia was able to hold in 1464 by a position under Venetian rule against the Ottomans until 1540. Thus Monemvasia is considered the last remnant of the former Eastern Roman Empire.
You can find the right literature here:
Lost to the West: The Forgotten Byzantine Empire That Rescued Western Civilization
Filled with unforgettable stories of emperors, generals, and religious patriarchs, as well as fascinating glimpses into the life of the ordinary citizen, Lost to the West reveals how much we owe to the Byzantine Empire that was the equal of any in its achievements, appetites, and enduring legacy.
For more than a millennium, Byzantium reigned as the glittering seat of Christian civilization. When Europe fell into the Dark Ages, Byzantium held fast against Muslim expansion, keeping Christianity alive. Streams of wealth flowed into Constantinople, making possible unprecedented wonders of art and architecture. And the emperors who ruled Byzantium enacted a saga of political intrigue and conquest as astonishing as anything in recorded history.
Lost to the West is replete with stories of assassination, mass mutilation and execution, sexual scheming, ruthless grasping for power, and clashing armies that soaked battlefields with the blood of slain warriors numbering in the tens of thousands.
The Cambridge History of the Byzantine Empire c.500-1492
Byzantium lasted a thousand years, ruled to the end by self-styled 'emperors of the Romans'. It underwent kaleidoscopic territorial and structural changes, yet recovered repeatedly from disaster: even after the near-impregnable Constantinople fell in 1204, variant forms of the empire reconstituted themselves. The Cambridge History of the Byzantine Empire c.500-1492 tells the story, tracing political and military events, religious controversies and economic change. It offers clear, authoritative chapters on the main events and periods, with more detailed chapters on outlying regions and neighbouring societies and powers of Byzantium. With aids such as maps, a glossary, an alternative place-name table and references to English translations of sources, it will be valuable as an introduction. However, it also offers stimulating new approaches and important findings, making it essential reading for postgraduates and for specialists. The revised paperback edition contains a new preface by the editor and will offer an invaluable companion to survey courses in Byzantine history.
The Byzantine Empire: A Complete Overview Of The Byzantine Empire History from Start to Finish
If you asked someone today when the Roman Empire ended, they might tell you 476 CE, the year that the final Roman Emperor in the west died. If you had asked someone at the time though, they might have told you that Rome was still very much alive—in Constantinople. The civilization known to us as the Byzantine Empire was known in its day as the continuation of Rome and everything it had represented. The Byzantines were not simply persistent Romans: they were their own distinct and long-lived society, both Roman and more. At its territorial zenith, it was an empire that spanned across the Mediterranean, and at its peak, it was the most powerful state in eastern Europe.
From Constantine’s founding of Constantinople in 330 CE to the city’s fall in 1453 CE, the city and all that was controlled from it had an impact on the world, well beyond its boundaries. As the second longest-lived empire in the history of the world, one might say that this was inevitable, but it was the leadership it had during the best periods in its history that truly made the difference. A truly captivating period, the history of the Byzantine Empire will give readers stories of order and chaos, glory and catastrophe, Paganism and Christianity.
A Cabinet of Byzantine Curiosities
Weird, decadent, degenerate, racially mixed, superstitious, theocratic, effeminate, and even hyper-literate, Byzantium has long been regarded by many as one big curiosity. According to Voltaire, it represented "a worthless collection of miracles, a disgrace for the human mind"; for Hegel, it was "a disgusting picture of imbecility."
A Cabinet of Byzantine Curiosities will churn up these old prejudices, while also stimulating a deeper interest among readers in one of history's most interesting civilizations. Many of the zanier tales and trivia that are collected here revolve around the political and religious life of Byzantium. Thus, stories of saints, relics, and their miracles-from the hilarious to the revolting-abound. Byzantine bureaucracy (whence the adjective "Byzantine"), court scandals, and elaborate penal code are world famous. And what would Byzantium be without its eunuchs, whose ambiguous gender produced odd and risible outcomes in different contexts? The book also contains sections on daily life that are equally eye-opening, including food (from aphrodisiacs to fermented fish sauce), games such as polo and acrobatics, and obnoxious views of foreigners and others (e.g., Germans, Catholics, Arabs, dwarves). But lest we overlook Byzantium's more honorable contributions to civilization, also included are some of the marvels of Byzantine science and technology, from the military (flamethrowers and hand grenades) to the theatrical ("elevator" thrones, roaring mechanical lions) and medical (catheters and cures, some bizarre). This vast assortment of historical anomaly and absurdity sheds vital light on one of history's most obscure and orthodox empires.