J. A. S. Evans 
Age of Justinian [PDF ebook] 
The Circumstances of Imperial Power

The Age of Justinian examines the reign of the great emperor Justinian (527-565) and his wife Theodora, who advanced from the theatre to the throne. The origins of the irrevocable split between East and West, between the Byzantine and the Persian Empire are chronicled, which continue up to the present day. The book looks at the social structure of sixth century Byzantium, and the neighbours that surrounded the empire. It also deals with Justinian’s wars, which restored Italy, Africa and a part of Spain to the empire.