How did Pisa and Genoa compete for influence in Sardinia?

Following the decline of external threats in the 11th century, the Italian maritime republics of Pisa and Genoa competed for dominance in Sardinia by forming strategic alliances with the island’s local rulers, known as giudici.1

Methods of Influence

• Territorial Zones: Pisa and Genoa established distinct spheres of influence, with Genoa primarily controlling the north and west, while Pisa dominated the south and east.1
• Political Maneuvering: The papacy supported Pisan influence by appointing the archbishop of Pisa as the primate of Sardinia in 1133. In response, Genoa sought to counter Pisan power by financing the coronation of Barisone I of Arborea as king of Sardinia in 1164.1
• Dynastic Alliances: Both republics utilized marriage and inheritance to secure control. For instance, the giudicati of Cagliari and Gallura eventually passed to Pisan families and the Pisan republic itself, while the giudicato of Torres shifted between Pisan and Genoese protection.1

Following the Battle of Meloria in 1284, Pisan influence was restricted to Cagliari and Gallura, while Genoa exerted control over the remaining districts through prominent noble families like the Doria, Spinola, and Malaspina.1