Following the administrative division of the Roman Empire in 395 AD, Crete became part of the Eastern Roman Empire, later known as the Byzantine Empire. Byzantine rule on the island is divided into two periods: the First Byzantine Period, from 395 until the Arab conquest of 824–827, and the Second Byzantine Period, from the Byzantine reconquest in 961 until the collapse of imperial authority following the Fourth Crusade in 1204.

The First Byzantine Period

During the First Byzantine Period, Crete largely retained the administrative and urban organisation of the Late Roman era. Gortyn remained the capital and the island’s most important administrative and ecclesiastical centre. Christianity, which had already spread during the preceding centuries, became firmly established, bishoprics were organised and numerous churches were constructed.

Among the most important monuments of this period is the large Early Christian Basilica of Saint Titus near Gortyn. Important remains have also been discovered at the Early Christian Basilica of Kastri in Hersonissos, the Basilica of Agia Sofia at Panormo, the Early Christian Basilica of Almyrida, the Basilica of Saint Panteleimon at Sougia and many other coastal and inland sites.

Large basilicas, mosaic floors, baptisteries and other ecclesiastical buildings bear witness not only to the spread of Christianity but also to the economic activity of the island’s towns. At the same time, several older urban centres gradually contracted as earthquakes, epidemics, economic changes and raids affected life on Crete.

The Emirate of Crete

The First Byzantine Period ended when Andalusian Muslim exiles, who had previously settled in Egypt, gradually conquered the island between 824 and 827. They established the Emirate of Crete and founded the fortified city of Chandax, at present-day Heraklion, as their capital. Despite repeated Byzantine campaigns, Arab rule continued for more than a century.

The Second Byzantine Period

In 960, a major military campaign was launched under the command of the general and future emperor Nikephoros Phokas. The Byzantine army landed on Crete and besieged the heavily fortified city of Chandax. The city was captured in March 961 and the island was reintegrated into the Byzantine Empire.

During the Second Byzantine Period, the island’s administration, defensive system and ecclesiastical life were reorganised. Bishoprics were restored, churches and monasteries were founded or renovated, and the fortifications of important towns and strategic locations were strengthened. Soldiers, members of the clergy and families from other parts of the empire settled on Crete and contributed to its economic and demographic recovery.

A characteristic monument of this period is the Byzantine Wall of Chania, which enclosed Kastelli Hill on the acropolis of ancient Kydonia. Comparable defensive works were constructed or strengthened in other parts of the island, as protection from maritime raids remained a major concern.

Byzantine rule effectively ended after Constantinople was captured by the Fourth Crusade in 1204. Sovereign rights over Crete were initially granted to Boniface of Montferrat, who transferred them to the Republic of Venice. Conflict with the Genoese followed, and the Venetians began establishing their authority over the island in 1211, opening a new period in Cretan history.