The political situation in central and southern Italy was complex. Since the end of the 9th century Sicily had escaped from the Eastern Roman Empire (Byzantine). It passed under total Muslim domination and served as a base for Saracen pirates reeking mayhem on the Italian coastline. The mainland of southern Italy was partly Byzantine (Calabria, Apulia, Basilicate and the coastal duchies of Campania) and partly Lombard (principalities of Capua, Benevento and Salerno).
The papacy, subject to the subjugation of the Holy Roman German Empire in the 10th century, under the Ottonian dynasty, was gradually liberating itself from its control and was playing an increasingly important and decisive political and moral role in society. The Benedictine monastery of Montecassino, which enjoyed great prestige and a real autonomy in the political arena wielded an important political influence in Mezzogiorno.
With the death of Henry II and the arrival of Conrad II in 1024, the Holy Roman German Empire, which controlled the northern half of Italy, saw a transition from the Ottonian dynasty of the Saxon emperors to those of the Salians. Their objective in southern Italy was to re-establish the authority of the Western Empire over Rome and the Lombard principalities and to overcome the Byzantine Empire and the Muslims of Sicily.
Following the arrival of the Lombards in Italy in the 6th century the political unity of the peninsula collapsed, and with it the final remnants of the Roman Empire. A Germanic people who had become Christian and spoke Latin, they settled in the Mezzogiorno in the interior of the duchy of Benevento. When Charlemagne conquered Parvia (in the north of the duchy) in 774, Arechis II, duke of Benevento (758-787), son-in-law of the last king of the Lombards, Didier, claimed his independence from the Franks, proclaimed himself prince and pitted himself against the expansionist Carolingians in southern Italy.
This boundary marked for a long time the limits of the imperial claims handed down from the Carolingians to the Ottonians and then to the Salians (Holy Roman German Empire). Following dynastic quarrels, the Lombard principality of Benevento experienced its first carving up in 849, with the creation of the principality of Salerno. Then in 981, the county of Capua obtained its independence. The small duchies of Naples, Amalfi and Gaeta, on the Tyrrhenian coast, were freed from Byzantine domination in the 8th and 9th centuries and were run by local dynasties.
At the beginning of the 11th century the only provinces that the Lombards had not seized were those under the control of the Eastern Roman Empire: the province of Longobardia (Apulia and Basilicate) whose population, were mainly Lombard, and Calabria, the only part retained from the province of Sicily, more Greek in character.
At the heart of this politically heterogeneous composition, the three most important Lombard states, whose princes, since the end of the 10th century or the beginning of the 11th century, considered themselves vassals of the German Empire, behaved in an unruly even confused fashion. While the Muslim menace loomed ever closer, they were not only involved in an ongoing war with the Byzantines and fighting against the enclaves of Naples Amalfi and Gaeta but also feuding amongst themselves. Their relationship with the papal seat was also hesitant.
Under the rule of Arab-Berber domination during the 9th century, Sicily, at the beginning of the 10th century was controlled by the Fatimids of Egypt, conquerors of North Africa. The government was entrusted to the Kalbite dynasty of Banu Abi l-Husayn who would be the ruling emirs for more than a century.
Following the failure of a Byzantine conquest in 965, a process of complete Arabisation of the island took place. This was made possible by an influx of Arabs and Berbers from North Africa and a policy of economic and fiscal development. Sicily conformed to the economic model of the principalities of the East: agricultural produce grown for the markets and the palace, importance given to luxury goods such as cotton and silk. Mazara, at the south-western tip of the island, was the central port for trade in the Mediterranean. Despite this, some Greek Christian communities managed to remain, in Palermo, Catania and in the Val Demon, in the northeast of the island.
The beginning of the 11th century saw the beginning of a period of serious political crisis in Sicily. Around 1030, the legitimacy of Fatimid rule was challenged and the Kalbite governors were expelled from the island. Dynastic quarrels between different emir factions led to political weakness that Byzantines used to their advantage. In 1038, helped by the Muslim faction, the Greeks launched another attempt to conquer the island. The expedition was led by the Greek general George Maniakes that contained three hundred Norman mercenaries provided by a Lombard prince, Guaimar IV of Salerno but it failed in 1040.
Having just emerged from a serious crisis in the 10th century, when the papal seat had become a victim of rival infighting between different aristocratic factions, the papacy had to address the internal reforms of the Church. During the second half of the 11th century an important period of Gregorian reform began. A long struggle followed between Rome and the German Empire, concerning the subject of the control of the ecclesiastic hierarchy, the question of the appointment of bishops, the quarrel about investiture – which was finally concluded favourably for the Church, at the beginning of the 12th century. Rome and the German Empire also claimed the legacy of the Roman Empire, and political supremacy over the Italian peninsula.
Confronted with the Norman presence, the papacy adopted, successively, two different manners of facing this problem: firstly demonstrating great hostility towards a single Italian state in the Mediterranean region under Norman control, and secondly, after the battle of Civitate in 1053, a rapprochement and even an alliance with the Normans.
The monastery of Montecassino was the most important and powerful religious institution in Italy, playing a dominant role in the relations between the Church and the Normans. The Terra Sancti Benedicti (Land of Saint-Benedict) was a compact seigniory extending from one sole tenant to an immense landed patrimony; in 1057 its power became even stronger when Pope Victor II, decreed that the abbot of Montecassino was to be pre-eminent over all the other abbots. Montecassino took a very cautious stance with regard to the Normans, yet on several occasions the abbots intervened as mediators in conflicts between the papacy and the Normans.
 M. Amari Storia del musulmani di Sicilia, volume iii, 2nd ed., Rome, 1939, pages 57-203 deals specifically with the Norman conquests (with a pro-Muslim bias) while F. Chalandon Histoire de la domination normande en Italie et en Sicile, two volumes, Librairie Alphonse Picard et fils (Librairie des Archives nationales et de la Société de l’École des Chartes), Paris, 1907 adopts a pro-Norman perspective.