Although marginalized by Catholicism , which became the dominant faith , this Greek - speaking Orthodox community survived into the 15th century .
These groups formed the basis for a local branch of the Orthodox Church , revived following Norman conquest in the 1120s .
Although marginalized by Catholicism , which became the dominant faith , this Greek - speaking Orthodox Church community survived into the 15th century .
These groups formed the basis for a local branch of the Orthodox Church , revived following Norman conquest in the 1120s .