AD 400-800 Early Byzantium

In AD 345, on the death of Theodosius I, the Roman Empire was divided into eastern and western halves. The two parts of the Empire had different rulers until the end of the Western Empire in about 476. The eastern, Byzantine, Empire was wealthier and stronger and was ruled from the great city of Constantinople. The city was founded as a ‘New Rome’ by Constantine the Great (reigned 306-337) in 330.

In the 6th century the emperor Justinian I (reigned 527-565) successfully, if expensively, recovered direct control of parts of Africa, Italy and Spain, and regained control of the Mediterranean. However, growing incursions and settlement by Slavs and Avars in the Balkan provinces and Greece caused the Empire problems from the 580s-90s. In the 7th century the ancient Roman rivalry with Persia culminated in the defeat of Persia by the emperor Heraclius (reigned 610-641), after decades of exhausting conflict which left both weakened empires vulnerable to the new power of Arab Muslims.

Persia collapsed and the Byzantine provinces in Syria, Egypt and North Africa also succumbed to the Arab armies. A new, powerful, Muslim state, the Umayyad caliphate, emerged. Constantinople survived Arab sieges in 674-8 and 717, which ensured the Empire’s survival and afterwards some Byzantine territory was recovered.