Theme (Byzantine district)

The themes or themata (Greek: θέματα; singular θέμα, thema) were the main administrative divisions of the middle Byzantine Empire. They were established in the mid-7th century in the aftermath of the Slavic invasion of Balkans and Muslim conquests of parts of Byzantine territory, and replaced the earlier provincial system established by Diocletian and Constantine the Great. In their origin, the first themes were created from the areas of encampment of the field armies of the East Roman army, and their names corresponded to the military units that had existed in those areas. The theme system reached its apogee in the 9th and 10th centuries, as older themes were split up and the conquest of territory resulted in the creation of new ones. The original theme system underwent significant changes in the 11th and 12th centuries, but the term remained in use as a provincial and financial circumscription, until the very end of the Empire.

History

Background

During the late 6th and early 7th centuries, the Eastern Roman Empire was under frequent attack from all sides. The Sassanid Empire was pressing from the east on Syria, Egypt, and Anatolia. Slavs and Avars raided Thrace, Macedonia, Illyricum and Greece and settled in the Balkans. The Lombards occupied northern Italy, largely unopposed. In order to face the mounting pressure, in the more distant provinces of the West, recently regained by Justinian I (r. 527–565), Emperor Maurice (r. 582–602) combined supreme civil and military authority in the person of an exarch, forming the exarchates of Ravenna and Africa. These developments overturned the strict division of civil and military offices, which had been one of the cornerstones of the reforms of Diocletian (r. 284–305). In essence however they merely recognized and formalized the greater prominence of the local general, or magister militum, over the respective civilian praetorian prefect as a result of the provinces' precarious security situation.