sentences:  In 1092, Pope Urban II raised the bishopric of Pisa to an archbishopric and gave it authority over the Corsican church.Pisa replaced the papal legates who were governing the island with judges ("judices") of their own appointment.Valuable chiefly as a source of timber for the Pisan fleet, but also as an important transit point for the slave trade, Corsica flourished under Pisan sovereignty, but crises soon arose.