The Byzantine Catholic Church in Italy is characterized by a unique phenomenon. Although Byzantine, this church has been under the jurisdiction of the bishop of Rome, the pope, since the sixth century – except for a period of 400 years beginning in 731. This Byzantine presence in southern Italy knows two phases: Italo-Greek and Italo-Albanian. These phases are clearly distinct for historical, cultural, ethnic and linguistic reasons, reflecting the general consciousness of the nation’s Byzantine Catholics.
The Italo-Greek Phase. The byzantinization of southern Italy began during the reign of Emperor Justinian I (527-565) with a military campaign launched by General Belisarius in 535. In time a Greek Church developed that had, at the peak of its power and influence in the 10th century, a number of dioceses and two metropolitan seats. The Greek Church had a substantial religious influence on southern Italy. The most recent studies of Italo-Greek saints, history, music and liturgy verify this influence with abundant documentation. Studies have also revealed that Greek monasticism, rivaling the monastic centers of the Byzantine East, thrived in 10th-century Calabria. The confluence in Italy of people from all over the empire – especially at the time of the seventh century Arab invasions – brought to Italy a variety of eastern, Byzantine traditions. Since provinces tend to be more conservative than city centers, southern Italy may be a true archive of ancient Byzantine traditions.