In the first century Roman Emperor Claudius divided the Roman province of Mauretania into Mauretania Caesariensis and Mauretania Tingitana along the line of the Mulucha (Muluya) River, about sixty kilometers west of modern Oran.

Under emperor Diocletian's Tetrarchy reform (293), the country is further divided in three provinces, as the small, easternmost region Sitifensis is split off from Mauretania Caesariensis.