The first Byzantine period lasted from 324 A.D. to 826 A.D. During this period Crete was part of the Byzantine Empire, the capital of which was Constantinople. The island became a separate province of the Empire and was governed by a Byzantine General. Christianity spread and was established on the island.
An important role in the spread of Christianity was played by Titus, the student of St. Paul, who was the first bishop of Crete. His activity contributed to the establishment of the new religion. Many churches were built during this period, mainly Basilicas. There are ruins of at least 40 Basilicas from this period. The most important ones are located in Gortyna, Itanos, Chersonisos, Sougia, Panormo, Elounda and Mitropolis.
source: archanes-asterousia.gr