At the end of the third century A.D., the Emperor Diocletian divided the great Roman province of Africa Proconsularis into smaller provinces, including Byzacena, corresponding now to the modern Sahel, region of Tunisia.

Hadrumetum (modern Sousse, Tunisia) became the capital of the the newly-made province. At this period the metropolis of Byzacena was after Carthage the most important town in Roman Africa.

Roman Africa Provinces

• Proconsularis (capital Carthage)
• Byzacena (capital Hadrumetum, modern Sousse)
• Tripolitana (including the island of Jerba)