Between the 1050s, when the Normans began to colonise southern Italy in earnest, and the death of the Empress Constance in 1198, the Latin Church in southern Italy was transformed. At the most obvious level, the conquest of Sicily had led to the re-Christianisation of the island and to the introduction of the Latin Church there. If the former process was not as yet complete by 1198, it was nevertheless already well advanced. The Greek churches of the former Byzantine provinces, and on Sicily, still existed, but as part of an ecclesiastical hierarchy subject to the pope at Rome. Furthermore the Latin episcopate and Latin rite were making inroads into formerly Greek territory, although in 1200 the Graecophone area was still substantial and its religious rite was to last for centuries to come.

Just as, if not more, striking a transformation had, however, affected the Latin Church itself. The confused, inchoate, institution of 1050 had been reorganised: a system of ecclesiastical provinces that had still been in its infancy in the early eleventh century, and confined to the Lombard principalities, had been extended over the whole region, new bishoprics had been founded, and the hierarchy of the secular Church brought under the supervision of the papal Curia. During the twelfth century individual dioceses became more structured, networks of subordinate churches and a type of parochial structure developed, albeit slowly.