The late Roman administrative system, as established by Diocletian, provided for a clear distinction between civil and military offices, primarily to lessen the possibility of rebellion by over-powerful provincial governors. Under Justinian I, the process was partially reversed for provinces which were judged to be especially vulnerable or in internal disorder. Capitalizing upon this precedent and taking it one step further, the emperor Maurice sometime between 585 and 590 created the office of exarch, which combined the supreme civil authority of a praetorian prefect and the military authority of a "magister militum", and enjoyed considerable autonomy from Constantinople. Two exarchates were established, one in Italy, with its seat at Ravenna (hence known as the Exarchate of Ravenna), and one in Africa, based at Carthage and including all imperial possessions in the Western Mediterranean. The first African exarch was the "patricius" Gennadius.