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Dioceses of Diocletian

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Dioceses of Diocletian

Diocese was the name given to the 12 new territorial divi sions of the Roman Empire in the provincial reforms of Diocletian. The problem of the provinces had long trou bled the rulers of Rome, as governors had rebelled and had seized the throne, while the Senate had not relin quished its own, albeit dwindling, influence with its own provinces. Diocletian resolved to end all such chaos, start ing reforms sometime around 293 A.D.

The number of provinces was doubled from 50 to 100, preventing any governor from amassing enough personal power to contemplate a revolt. To further ensure the loy alty of the governors, all provinces ceased to be either im perial or senatorial and henceforth would be grouped into large units called dioceses. Each diocese contained several provinces, and each provincial head was answerable to the official of the diocese, the vicani praetectorum praetoria, or just vicani. Each of the vicani,in turn, reported to one of the four Praetorian Prefects assigned to the four members of the tetrarchy, an Augustus and a Caesar, both in the East and in the West.

Thus, no government official was ever isolated or en dowed with enough strength to ponder the possibilities of an uprising. Further, the dioceses facilitated Diocletian’s desire for increased centralization and the aggrandizement of the central imperial government at the expense of the Senate and provinces. The dioceses stretched across traditional geographical, hence cultural, borders. Oriens con tained Mesopotamia, Syria, Palestine, Egypt and Libya, while Hispania contained all of Spain and part of Africa, namely the small coastal privince of Mauretania Tingitana.

Italy, previously held sacred and separate from the Em pire as a bastion of elitism, lost its special status. Not only was it now placed under direct imperial supervision, it was also cut in half to make two dioceses. Finally, as the Roman world had been divided into East and West, the nu merical discrepancy of eight dioceses in the West, as compared to five in the East, was offset by the reality that economic superiority rested with the provinces of Greece,


Name of Diocese




Libya, Egypt, Palestine, Syria, and Cilicia


Cappadocia, Armenia Minor, Galatia, Bithynia

Asia (Asiana)

Asia, Phrygia, Pisidia, Lycia, Lydia, Caria


Moesia Inferior, Thrace


Moesia Superior, Dacia, Epirus, Macedonia, Thessaly, Achaea, Dardania



Tripolitana, Africa Proconsularis, Numidia, part of Mauretania


Mauretania Tingitana, Baetica, Lusitania, Tarraconensis


Narbonensis, Aquitania, Viennensis, Alpes Maritime


Lugdunensis, Germania Superior, Germania Inferior, Belgica


Britannia, Caesariensis, Italia Liguria, Venetia, Alpes Cottiae, Alpes Graiae, Raetia


Pannonia Inferior, Pannonia Superior, Noricum, Dalmatia


Umbria, Campania, Sicilia, Corsica, Sardinia

The Monetary History of the World
© Martin A. Armstrong