Complex sentence: Genoa was one of the so-called "Maritime Republics" ("Repubbliche Marinare"), along with Venice, Pisa and Amalfi and trade, shipbuilding and banking helped support one of the largest and most powerful navies in the Mediterranean.
Split into simpler sentences: Genoa was one of the so-called "Maritime Republics" ("Repubbliche Marinare"), along with Venice, Pisa, and Amalfi. Trade, shipbuilding, and banking helped support one of the largest and most powerful navies in the Mediterranean.