The Republic of Pisa was a de facto independent state centered on the Tuscan city of Pisa during the late 10th and 11th centuries. It rose to become an economic powerhouse, a commercial center whose merchants dominated Mediterranean and Italian trade for a century before being surpassed and superseded by Genoa. The power of Pisa as a mighty maritime nation began to grow and reached its apex in the 11th century when it acquired traditional fame as one of the four main historical Maritime Republics of Italy.