During the Roman Empire, Thera was little more than a small, insignificant island. However, when Christianity reached the island early, an organized church was established by the 4th century A.D. The island had neither political nor military significance in Byzantine times, although Alexius I Comnenus [1081 - 1118] founded the church of the Panagia Episkopi at Gonia. After the fall of Constantinople in the Fourth Crusade [1204], the Duchy of Naxos was founded and Thera became the seat of one of the four Catholic Bishops of the Duchy. The name Santorini was given at that time by the Crusaders, named after a small chapel of Agia Irini [Santa Irene] which some say was at Perissa and others say it was at Riva on Therasia. 