These provinces were Zeugitana (the former Proconsularis), Carthage, Byzacium, Tripolitana, Numidia and 1Vlauretania.
After his death in 33, Numidia was made a Roman province.
In Africa their empire included Egypt, Carthage, Numidia and Mauritania.
Towards 194 Septimius Severus completed the reform of Caligula by detaching from the province of Africa the greater part of Numidia to constitute a special province governed by a procurator, subordinate to the imperial legate and resident at Cirta (Tissot ii.
During the African war they invaded Numidia and conquered Cirta, the capital of the kingdom of Juba, who was thus obliged to abandon the idea of joining Metellus Scipio against Caesar.
Of Numidia (see under Juba), with the river Ampsaga as the eastern frontier (Plin.
Augusta, and the most important strategic centre, as commanding the passes of the Mons Aurasius, a mountain block which separated Numidia from the Gaetulian tribes of the desert, and which was gradually occupied in its whole extent by the Romans under the Empire.
The chief towns of Numidia under the Romans were: in the north, Cirta, the capital, which still retains the name Constantine given it by Constantine; Rusicada on the coast, serving as its port, on the site now occupied by Philippeville; and east of it Hippo Regius, well known as the see of St Augustine, near the modern Bona.
In Diocletian's great reform of the administrative system of the empire, the whole of Roman Africa, with the exception of Mauretania Tingitana (which was attached to the province of Spain), constituted a single diocese subdivided into six provinces: Zeugitana (Carthage), Byzacium (Hadrumetum, now Susa), Numidia Cirtensis (Cirta, Constantine), Tripolitana (Tripolis), Mauretania Sitifensis (Sitifis, Setif), and Mauretania Caesariensis (Caesarea, now Cherchel).
Thus the dividing line between the two provinces was the same as that which had originally separated Mauretania from Numidia (q.v.).