I have included only a few items concerning the history of this empire. A good source for more details can be
found on Wikipedia or in history books.
In 286 AD, Emperor Diocletian divided the original
Roman empire into two separate political entities: Byzantine or eastern empire;
Rome or western empire. The eastern capital at Constantinople
strategically commanded entrance through the Dardanelles.
The city (now called Istanbul) previously was a
Greek city called Byzantium.
In 657 BC, colonists from Megara in Attica founded the city.
In 330 AD, Emperor Constantine made Byzantium his capital
and renamed the city Constantinople. He also ordered construction of the city's massive walls
and granted Christianity preferential treatment.
In 332 AD, Constantine defeated Visigoths of Gutthiuda and reconquered southern
Dacia. Barbarian tribes often threatened and clashed with Byzantine forces.
The Battle of Adrianople on 9 August 378 AD was a
turning point, when Gothic rebels destroyed an army under Emperor Valens. Emperor
Theodosius I later made peace with various groups (including annual tribute to
Huns under Attila), which lasted until his death in 395 AD.
Alaric I, king of the Visigoths (395-410 AD) lost 10,000 troops while helping
Theodosius defeat Franks in battle at Frigidus.
Receiving nothing for his assistance, Alaric sacked numerous cities in Greece,
including Corinth and Sparta.
Byzantine Emperor, Flavius Arcadius, quickly granted Alaric control of
Illyricum. Alaric later invaded Italy, received large payments from
the western empire, and eventually sacked Rome in 410 AD.
Attila's empire collapsed after his death in 453 AD, but Germanic and other tribes continued a migration into the western
Roman empire. Byzantine emperor Zeno claimed rule over the entire Roman empire and
encouraged king Theodoric of the Ostrogoths to conquer Italy, where general
Odoacer seized control and refused to accept Zeno's dominion. Theodoric overthrew
Odoacer in 493 AD and reigned over an Ostrogoth Kingdom.
Between 527 and 565 AD, Justinian I ruled and expanded the Byzantine Empire.
His best general, Belisarius, succeeded in north Africa against the
Vandals and the Goths in Italy. Byzantine troops also assisted
Visigoths in Spain,
winning a portion in the south. Belisarius, coming out of retirement, repelled Kutrigur Huns along the
Danube River. Justinian caused resettlement in the northwest
Balkans of Croats and Serbs.
During his reign, the Hagia Sophia was built.
Byzantine borders shrank under the reign of Heraclius (610-641 AD).
Shortly after his accession, Sassanid forces occupied
Jerusalem. The invaders later were
destroyed in battle at Nineveh in 627 AD. The war weakened both
empires, which suffered from invading Muslims. They crushed a Byzantine
army at Yarmouk and seized Ctesiphon.
Islamic forces then conquered the Levant. A century later they laid siege to
Constantinople (717-718 AD). The two forces clashed repeatedly until
Constantinople fell in 1453 AD and the vestigial Byzantine Empire collapsed.