Mauri (from which derives the English term "Moors") was the Latin designation for the Berber population of Mauretania, located in the west side of North Africa on the shores of the Mediterranean Sea, Mauretania Tingitana and Mauretania Caesariensis, in the North of present-day Morocco and north western Algeria.

Mauri (Μαῦροι) by Strabo, who wrote in the early 1st century, as the native name, which was also adopted into Latin, while he cites the Greek name for the same people as Maurusii (Μαυρούσιοι). The name Mauri as a tribal confederation or generic ethnic designator thus seems to roughly correspond to the people known as Numidians in earlier ethnography; both terms presumably group early Berber-speaking populations (the earliest Libyco-Berber epigraph dates to about the third century BC).

In 44 AD, the Roman Empire incorporated the region as the province of Mauretania, later divided into Mauretania Caesariensis and Mauretania Tingitana. The area around Carthage was already part of Africa Proconsularis. Roman rule was effective enough so that these provinces became integrated into the empire.

Mauri raids into the southern Iberian Peninsula are mentioned as early as the reign of Nero in the Eclogues of Calpurnius Siculus: "Geryon's meads, a wealthy prize to tempt the fierce Moor's avarice, where Baetis huge, so legends say, rolls downward on his western way to find the shore." The Baetis is the modern Guadalquivir, so this poem implies Mauri raiding into Baetica in the first century CE. Mauri from the mountains beyond the border of the Roman Empire crossed the straits of Gibraltar to raid into the Roman province of Baetica, in what is today southern Spain, in the early 170s. Mauri raided Baetica again in the late 170s or 180s in the reign of Commodus. At that time they besieged the town of Singilia Barba, which was freed from the siege by the arrival of Roman troops from the province of Mauretania Tingitana, led by C. Vallius Maximianus.

By the early Christian era, the byname Mauritius identified anyone originating in Africa (the Maghreb), roughly corresponding to Berber populations. Two prominent "Mauritian" churchmen were Tertullian and St. Augustine. The 3rd-century Christian saint Mauritius, in whose honour the given name Maurice originated, was from Egypt.

When Aurelian marched against Zenobia in 272, his army included Moorish cavalry. The Notitia Dignitatum mentions Roman cavalry units called Equites Mauri, or Moorish cavalry. Many Mauri were enlisted in the Roman army and were well known as members of the comitatus, the emperor's mobile army, prior to the reign of Diocletian. Jones cites the record of a consular interrogation from Numidia in 320, in which a Latin grammarian named Victor stated that his father was a decurion in Cirta (modern Constantine), and his grandfather served in the comitatus, 'for our family is of Moorish origin'.

By the time of Diocletian, Moorish cavalry were no longer part of the mobile field army, but rather were stationed along the Persian and Danube borders. There was one regiment of Equites Mauri in "each of the six provinces from Mesopotamia to Arabia". The Mauri were part of a larger group called Equites Illyricani, indicating previous service in Illyricum.

While many Mauri were part of the Roman empire, others resisted Roman rule. As Gibbon related for the years 296–297, "From the Nile to Mount Atlas, Africa was in arms." Diocletian's co-emperor Maximian campaigned against the Mauri for two years, entering into their mountain fastness to terrify them of Rome's power. This may be the reason why the border legions of northwest Africa were reinforced in Diocletian's time with seven new legions spread through Tingitania, Tripolitania, Africa, Numidia, and the Mauritanias.