Under Septimius Severus (193), Numidia is separated from Africa Vetus, and governed by an imperial procurator.

Under the new organization of the empire by Diocletian, Numidia is divided in two provinces: the north becomes Numidia Cirtensis, with capital at Cirta, while the south, which includes the Aurès Mountains and is threatened by raids, becomes Numidia Militiana, "Military Numidia", with its capital at the legionary base of Lambaesis.

Subsequently however, Emperor Constantine the Great reunites the two provinces in a single one, administered from Cirta, which is now renamed Constantina (modern Constantine, Algeria) in his honor.

Its governor is raised to the rank of consularis in 320, and the province remains one of the seven provinces of the diocese of Africa until the invasion of the Vandals in 428, which begins its slow decay, accompanied by desertification.

It is restored to Roman rule after the Vandalic War, when it becomes part of the new praetorian prefecture of Africa.