The Byzantine Exarthate of Carthage and the Arab conquest of North Africa

The Exarchate of Africa or of Carthage, after its capital, was the name of an administrative division of the Eastern Roman Empire encompassing its possessions on the Western Mediterranean, ruled by an exarch, or viceroy. It was created by emperor Maurice in the late 580s and survived until itsconquest by the Muslims in the late 7th century. Northwestern Africa, along with Sardinia, Corsica and the Baleares was reconquered by the East Romans under Belisarius in the Vandalic War of 533, and reorganized as the Praetorian prefecture of Africa by Justinian I. It included the provinces of Africa Proconsularis, Byzacena,Tripolitania, Numidia, Mauretania Caesariensis  and Mauretania Sitifensis, and was centered atCarthage. In the 560s, a Roman expedition succeeded in regaining parts of southern Spain, which were administered as the new province of Spania. After the death of Justinian, the Empire came into increasing attacks on all fronts, and the remoter provinces were often left to themselves to cope as best as they could, with Constantinople unable to provide assistance. The Late Roman administrative system, as established by Diocletian, provided for a clear distinction between civil and military offices, primarily to lessen the possibility of rebellion by over-powerful provincial governors. Under Justinian I, the process was partially reversed for provinces which were judged to be especially vulnerable or in internal disorder. Capitalizing upon this precedent and taking it one step further, the emperor Maurice sometime between 585 and 590 created the office of exarch, which combined the supreme civil authority of a praetorian prefect and the military authority of a magister militum, and enjoyed considerable autonomy from Constantinople. Two exarchates were established, one in Italy, with seat at Ravenna (hence known as the Exarchate of Ravenna), and one in Africa, based at Carthage and including all imperial possessions in the Western Mediterranean. The first African exarch was the patricius Gennadius. Among the provincial changes, Tripolitania was detached from Africa and placed under the province of Egypt, Mauretania Caesariensis and Mauretania Sitifensis were merged to form the new province of "Mauretania Prima", while Maretania Tingitana, effectively reduced to the city of Septum (Ceuta), was combined with the citadels of the Spanish coast (Spania) and the Balearic islands to form "Mauretania Secunda".The Visigothic kingdom in Spain was also a continuous threat. The African exarch was in possession of Mauretania II, which was little more than a tiny outpost in southern Spain. The conflict continued until the final conquest of the last Spanish strongholds in c. 624 by the Visigoths. The Byzantines retained only the fort of Septum (modern Ceuta), acrossGibraltar. During the successful revolt of the exarch of Carthage Heraclius and his namesake son Heraclius in 608, the Amazigh comprised a large portion of the fleet that transported Heraclius to Constantinople. Due to religious and political ambitions, the Exarch Gregory the Patrician (who was related by blood to the imperial family, through the emperor's cousin Nicetas) declared himself independent of Constantinople in 647. At this time the influence and power of the exarchate was exemplified in the forces gathered by Gregory in the battle of Sufetula also in that year where more than 100,000 men of Amazigh origin fought for Gregory. The first Islamic expeditions began with an initiative from Egypt under the emir 'Amr ibn al-'Asand his nephew Uqba ibn Nafi. Sensing Roman weakness they conquered Barca, in Cyrenaica, then successively on to Tripolitania where they encountered resistance. Due to the unrest caused by theological disputes concerning  Monothelitism  and Monoenergism the Exarchate under Gregory the Patrician distanced itself from the empire in open revolt. Carthage being flooded with refugees from Egypt (especially Melkites), Palestine and Syria exacerbated religious tensions and further raised the alarm to Gregory of the approaching Arab threat. Sensing that the more immediate danger came from the Muslim forces Gregory gathered his allies and initiated a confrontation with the Muslims and was defeated at the Battle of Sufetula, which was actually the capital of the exarchate since Gregory had moved to the interior for a better defense against Roman counter-offensives from the sea. Afterwards the Exarchate became a semi-client state under a new Exarch called Gennadius. Attempting to maintain tributary status with Constantinople and Damascus strained the resources of the Exarchate and caused unrest amongst the population. The peak of resistance reached by the exarchate with assistance from its Berber allies of kingKusaila was the victory over the forces of Uqba Ibn Nafia at the Battle of Biskra in 682. The victory caused the Muslim forces to retreat to Egypt, giving the Exarchate a decade's respite. The repeated confrontations took their toll on the dwindling and ever-divided resources of the Exarchate. In 698, the Muslim commander Hasan ibn al-Nu'man and a force of 40,000 men crushed Roman Carthage. Many of its defenders were Visigoths sent to defend the Exarchate by their king, who also feared Muslim expansion. Many Visigoths fought to the death; in the ensuing battle Roman Carthage was again reduced to rubble, as it had been centuries earlier by the Romans. The loss of the mainland African Exarchate was an enormous blow to the Byzantine empire in the Western Mediterranean because both Carthage and Egypt were Constantinople's main sources of manpower and grain. It was also an enormous blow because it permanently ended Roman presence in Africa. The conventional historical view is that the conquest of North Africa by the Islamic Umayyad Caliphate between AD 647–709 effectively ended Catholicism in Africa for several centuries.The prevailing view is that the Church at that time lacked the backbone of a monastic traditionand was still suffering from the aftermath of heresies including the so-called Donatist heresy, and that this contributed to the early obliteration of the Church in the present day Maghreb.Some historians contrast this with the strong monastic tradition in Coptic Egypt, which is credited as a factor that allowed the Coptic Church to remain the majority faith in that country until around after the 14th century despite numerous persecutions. However, new scholarship has appeared that disputes this. There are reports that the Roman Catholic faith persisted in the region from Tripolitania (present-day western Libya) to present-day Morocco for several centuries after the completion of the Arab conquest by 700. A Christian community is recorded in 1114 in Qal'a in central Algeria. There is also evidence of religious pilgrimages after 850 to tombs of Catholic saints outside of the city of Carthage, and evidence of religious contacts with Christians of Arab Spain. In addition, calendrical reforms adopted in Europe at this time were disseminated amongst the indigenous Christians of Tunis, which would have not been possible had there been an absence of contact with Rome. Local Catholicism came under pressure when the Muslim fundamentalist regimes of theAlmohads and Almoravids came into power, and the record shows persecutions and demands made that the local Christians of Tunis to convert to Islam. We still have reports of Christian inhabitants and a bishop in the city of Kairouan around 1150 – a significant report, since this city was founded by Arab Muslims  around 680 as their administrative center after their conquest. A letter in Catholic Church archives from the 14th century shows that there were still four bishoprics left in North Africa, admittedly a sharp decline from the over four hundred bishoprics in existence at the time of the Arab conquest. Berber Christians continued to live in Tunis and Nefzaoua in the south of Tunisia until the early 15th century, and "[i]n the first quarter of the fifteenth century, we even read that the native Christians of Tunis, though much assimilated, extended their church, perhaps because the last of the persecuted Christians from all over the Maghreb had gathered there." By 1830, when the French came as conquerors to Algeria and Tunis, local Catholicism had been extinguished. The growth of Catholicism in the region after the French conquest was built on European settlers, and these immigrants and their descendants mostly left when the countries of the region became independent.
Πηγη: https://en.m.wikipedia.org/wiki/Exarchate_of_Africa
https://en.m.wikipedia.org/wiki/Muslim_conquest_of_the_Maghreb