Chronology of Catholic Dioceses:Notes on the Diocese of Tricala / Triocala

The first known bishop of Tricala (or Triocala; now called Caltabellotta) in Sicily is a legendary St. Pellegrino (3rd century). The next known bishop is a Peter, mentioned in the letters of Pope Gregory the Great. The last known bishop was a John, present at the Second Council of Nicea (787).

The see was probably abandoned because of the Saracene conquest in 837. Early after 1087, the see of Agrigento (Girgenti) was reeastablished, and Triocala was put under its jurisdiction.

In 1090 its territory was given to the "Archimandritate" of Santissimo Salvatore, a Byzantine Abbacy with eventually had jurisdiction over several small territories around churches and monasteries all throughout Sicily and parts of Calabria. At some later time, it was transferred back to the diocese of Agrigento, which makes more sense geographically.

(Sources: Research of Mr. Giulio Longo,
http://www2.chiesacattolica.it/diocesi/agrigento/diocesi.htm (Website discontinued)
Website of the Archdiocese of Messina
http://www.mediatel.it/provincia.agrigento/caltabelc.html
http://digilander.iol.it/muleweb/castelve.htm
Website of Commune di Agirgento; no longer available