Pola has slowly gone into decline, its decay accelerated by the infighting of local families: the ancient Roman Sergi family and the Ionotasi (1258–1271) and the clash between Venice and Genoa for the control of the city and its harbor in the late thirteenth and  fourteenth centuries.

Patriarch Raimondo della Torre in 1291, by the Peace of Treviso, had gained the city as part of the secular realm of the Patriarchate of Aquileia, only to lose it to Venice in 1331, which will hold it until its downfall in 1797.