During a great part of the eleventh century, Bari, and in a lesser degree Trani, Brindisi and Taranto, had traded with the East; while so long as Amalfi remained nominally subject to the Greek Emperors, she enjoyed special advantages which enabled her to compete successfully with all her rivals. Only after her submission to Robert Guiscard, in 1073, was she forced to yield the premier place to Venice, which for the next two decades possessed what was practically a monopoly of the Levant trade. Scarcely, however, had the supremacy of Venice been established than it was challenged by Genoa and Pisa. Having swept the infidel from the Western Mediterranean, they were ready for fresh enterprises, and the preaching of the First Crusade pointed to the East.

At this time Pisa stood high in the favour of the Holy See. In 1091, at the prayer of the well-beloved daughter of St Peter, the Countess Matilda, of Bishop Daibert and of the Pisan nobles, Urban II leased the island of Corsica to the Pisan Church for an annual rent of fifty pounds of Lucchese money, payable at the Lateran Palace. In the following year the diocese of Pisa was erected into an Archbishopric with jurisdiction over the prelates of Corsica.