In the early 600s AD, the Byzantine Empire entered a period of serious crises that would alter the future of Tunisia. For centuries Rome/Byzantium's greatest enemy had been the Sassanid Persians, and the two powers were chronically atwar with each other. The warfare was often intense but usually resulted in small border changes. By the 7th century however, the situation changed dramatically. Persistent religious discord within the Empire, followed by the overthrow of Emperor Maurice by the tyrant Phocas, severely weakened the Byzantines. The Persians invaded the Byzantine Empire, in alliance with the Eurasian Avars and Slavs from the north. Much of the Empire was overrun and it seemed the end was near.
