Roman Province

Roman Imperial Provinces

During the Empire, the number and size of provinces changed according with internal Roman politics. The biggest or more garrisoned provinces (example Pannonia and Moesia) were subdivided into smaller provinces in order to prevent the situation whereby a sole governor held too much power in his hands, thus discouraging ambition for the Imperial throne itself.

With the formation of the Principate after the civil wars which ended the Roman Republican period, Augustus retained the power to choose governors for the provinces in which he and his successors held supreme military and administrative control. Thus the more strategically critical provinces, generally located along the contested borders of the Empire, became Imperial provinces. The remaining provinces were maintained as Senatorial provinces, in which the Senate had the right to appoint a governor.

List of Roman provinces in 120 a.D.

Hispania Baetica
Lusitania
Hispania Terraconensis
Gallia Narbonensis (the Roman province; the term persists in the medieval and modern name Provence)
Gallia Aquitania
Gallia Lugdunensis
Gallia Belgica
Britannia
Germania Inferior
Germania Superior
Raetia
Italia
Sicilia
Corsica et Sardinia
Alpes Poeninae
Alpes Cottiae
Alpes Maritimae
Noricum
Pannonia
Dalmatia
Dacia
Moesia
Thracia
Macedonia
Epirus
Achaea
Asia
Bithynia
Galatia
Lycaonia
Lycia
Pisidia
Pamphylia
Cilicia et Cyprus
Cappadocia
Pontus
Armenia Inferior
Sophene
Osroene
Commagene
Syria
Iudaea
Arabia Petraea
Aegyptus
Cyrenaica (including Crete)
Numidia
Africa
Mauretania
Baleares (province)

List of Roman Provinces till 400 a.D.

Although emperor Diocletian's reform known as Tetrarchy (284-305; a western and eastern Augustus, each seconded by a Caesar, each defending and administering a quarter of the empire) was not to last, the four quarters were definitely reinstored in 318 by emperor Constantine the Great, as pretorian prefectures, though under only two emperors (final division by Theodosion in 395 a.D.); their two capitals, Rome (again, but in the end de facto left for Ravenna) and (since 359) Constantinople, each had a special governor, with the ancient style Praefectus Urbis.

Diocletian's original 12 dioceses (each under a Vicarius) also persisted, but three more were created by splits in the fourth century (in the Western empire Italia was split in two and in the east Egypt was detached from Oriens).

Praetorian prefecture of Galliae

Diocese of Britanniae

Maxima Caesariensis
Valentia
Britannia Prima
Britannia Secunda
Flavia Caesariensis

Diocese of Galliae

In France:

Lugdunensis I
Lugdenensis II
Lugdunensis III
Lugdunensis IV

all of Belgium and Luxemburg and the Netherlands south of the Rhine:

Belgica I
Belgica II

Germany west of the Rhine:

Germania I
Germania II

Switzerland ('Helvetic' tribes):

Alpes Penniae et Graiae
Maxima Sequanorum

Diocese of Viennensis

Viennensis
Alpes Maritimae
Aquitanica I
Aquitanica II
Novempopulana
Narbonnensis I
Narbonnensis II

Diocese of Hispaniae

In modern Spain:

Baetica
Gallaecia (Conventus Lucensis, north of the Minho river)
Tarraconensis
Carthaginiensis
Baleares

In modern Portugal:

Lusitania (also covers Extremadura in Spain)
Gallaecia (Conventus Bracarensis, south of the Minho river)

In modern Morocco:

Mauretania Tingitana or Hispania Nova

Praetorian prefecture of Italia et Africa (western)

Diocese of Italia annonaria

Venetia and Istria
Aemilia
Liguria
Flaminia and Picenum Annonarium
Alpes Cottiae
Raetia I
Raetia II

Diocese of Italia suburbicaria

Campania
Tuscania et Umbria
Picenum Suburbicarium
Apulia et Calabria
Bruttia et Lucania
Samnium
Valeria
Corsica
Sicilia
Sardinia

Diocese of Africa

Africa proconsularis
Byzacena
Mauretania Caesariensis
Numidia
Tripolitana

Prefecture of Illyricum

Eastern, but disputed since 337; the original diocese of Moesiae was split in two dioceses: Macedonia and the latest aquisition, Dacia.

Diocese of Pannoniae

This had been the only diocese in the eastern quarters of the tetrarchy not belonging to the cultural Greek half of the empire, and was transferred to the western empire when Theodosius fixed the final split in 395

Dalmatia
Noricum mediterraneum
Noricum ripense
Pannonia I
Pannonia II
Savia
Valeria ripensis

Diocese of Dacia

Dacia mediterranea
Moesia I
Praevalitana
Dardania
Dacia ripensis

Diocese of Macedonia

Macedonia
Creta
Thessalia
Epirus vetus
Epirus nova
Macedonia Salutaris
Achaea

Prefecture of Oriens

Diocese of Thraciae

The eastern-most corner of the Balkans that was not part of the (western) Illyricum prefecture

Europa
Thracia
Haemimontium
Rhodope
Moesia II
Scythia

Diocese of Asiana

Asia in antiquity stands for Anatolia.

Pamphylia
Caria
Lydia
Lycia
Lycaonia
Pisidia
Phrygia Pacatiana
Phrygia Salutaria
Asia
Hellespontus
Insulae (Aegean islands)

Diocese of Pontus

The name is latinize from Greek Pontos (Euxinos), i.e. the (Black) Sea. Indeed it mainly contains parts of Asia minor near those coasts as well as the mountainous centre of Turkey.

Bithynia
Galatia
Paphlagonia
Honorias
Galatia Salutaris
Cappadocia I
Cappadocia II
Helenopontus
Pontus Polemoniacus
Armenia I
Armenia II

Diocese of Oriens

It comprise mainly the modern Arabic Machrak (Syria, Lebanon, Iraq, Palestine/-Israel and Jordan:

Palestina I
Palestina II
Palestina Salutaris
Syria
Syria Salutaris
Phoenicia
Phoenicia Libani
Eufratensis
Osrhoene
Mesopotamia
Arabia
Cilicia I
Cilicia II
Isauria
Cyprus

Diocese of Aegyptus

Egypt was the only diocese that wasn't under a vicarius, but whose head retained the unique title of Praefectus Augustalis, previously at the governor's level.

Aegyptus: Lower Egypt, previously two provinces, named after the pagan titles of the two emperors under Diocletian: Aegyptus Iovia (from Juppiter, for the Augustus; with the metropole Alexandria) and Aegyptus Herculia (for his junior, the Caesar; with ancient Memphis). Augustamnica is a part of the delta (thirteen 'cities'), split off - the only Egyptian province under a Corrector (lowest ranking governor)
Thebais: Upper Egypt; Nubia south of Philae had been abandoned to tribal people
Arcadia
Libya Superior
Libya Inferior