The Republic of Pisa (Italian: Repubblica di Pisa) was a de facto independent state centred on the Tuscan city of Pisa, which existed from the 11th to the 15th century. It rose to become an economic powerhouse, a commercial centre whose merchants dominated Mediterranean and Italian trade for a century, before being surpassed and superseded by the Republic of Genoa.
The republic’s participation in the Crusades secured valuable commercial positions for Pisan traders, thereafter the city grew in wealth and power. Pisa was a historical rival to Genoa at sea and to Florence and Lucca on land.
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 main historical Maritime Republics of Italy.
The rivalry between Pisa and Republic of Genoa intensified in the 13th century and resulted in the naval Battle of Meloria (1284), fought right in front of the Pisan port, which marked the beginning of the decline of the power of the city, with the renunciation of any claim on Corsica and with the sale of part of Sardinia to Genoa in 1299. Furthermore, from 1323, the Aragonese conquest of Sardinia began, which deprived the city of the dominion over the giudicati of Cagliari and Gallura.
Given the difficult economic and political situation of the now decadent Republic, on February 13, 1399, the lord of Pisa Gherardo Appiani sold the city and the countryside for the sum of 200,000 gold florins to Gian Galeazzo Visconti of the Pisan branch of the Visconti family to become lord of Piombino and obtain the appointment as Lord of Pisa. However, the control of the Republic by the Visconti did not last long, in fact Pisa maintained its independence and dominion over that part of the Tuscan coast and beyond until 1406, when it was occupied by the mercenaries Angelo Tartaglia and Muzio Attendolo Sforza who ordered the annexation to the Republic of Florence.