until Xl sec. to dominate maritime traffic in the Mediterranean were the Arabi.ma after Mille four Italian cities: Amalfi, Pisa, Genoa and Venice.the four Italian cities depended on the Roman German Empire Sacred (Pisa, and Genoa) or from the Byzantine Empire (Amalfi and Venice), but at the time of the Saracen pirates and Normans had received no protection from the authorities to which they were subjected, and had due aunomamente then organize to defend themselves.

From the 10th to the 13th centuries they built fleets of ships both for their own protection and to support extensive trade networks across the Mediterranean, giving them an essential role in the Crusades.