In the tenth century, Byzantium still had substantial possessions in southern Italy: the Catepanate kept its own private law and its Latin language and rite, while the theme of Calabria was thoroughly Hellenized. They developed a strong sense of independence, due to bad government and the failure of the Empire to defend them against Arab raids, except by paying tribute. In the eleventh century, written sources and archaeology reveal a multiplication of fortified settlements and refuges, built by public and religious authorities, and also by the aristocracy, but the increased presence of professional military units increased local dissension. The only large estates belonged to a few Calabrian bishoprics. The main difference between the two provinces lay in the syncopated chronology of their evolution. The Apulian economy grew in the tenth century, with the development of the ports on the Adriatic and the Mediterranean oil trade, which enriched notables, at a time when Calabria was being devastated by the Arabs. After a fortification campaign and some fiscal and military measures provided by Byzantium, the Calabrian economy prospered, exporting wheat, raw silk, iron, and gold. The Arabs moved their attacks north, targeting Apulia, which was in the grip of civil war: in each city the anti-Byzantine faction revolted with the support of Lombards and local conterati troops. In Calabria, administration and defence fragmented and were taken over, in the case of towns, by virtually autonomous kastra, and, in the countryside, by the aristocracy.