The Maltese Islands were incorporated into the Byzantine province of Sicily by 535. Melite remained the administrative centre of the island, but little is known about Byzantine period in the city. They might have built a retrenchment which reduced Melite to the size of present-day Mdina, one third of the size of the Punic-Roman city. The retrenchment was probably built in around the 8th century to counter the increasing Muslim threat, although it might have been built later on in around the 11th century by the Arabs. Regardless when the retrenchment was built, the new walls were most likely built out of stones taken from demolished buildings of the ancient city.