The history of Pisa passes through centuries of economic and cultural splendor, interspersed with suffocating dominations that have led to periods of degradation and abandonment. Despite its tormented and turbulent past, the city preserves works of enormous artistic and cultural value, admired and appreciated by millions of tourists from all over the world. The name 'Pisa' probably derives from the Etruscan and means 'mouth', 'estuary'; the association is due to the position in which the city once stood right on the mouth of the Arno. Among the various hypotheses formulated to identify the historical origins, the most accredited seems to be the one that sees Pisa as an Etruscan river port, around the middle of the 6th century BC; even if in reality the presence of residential nuclei is evidenced as early as around the 9th century BC. The navigability of the river and the proximity of the sea have allowed a flourishing development of trade, alongside equally flourishing artisanal activities and the production of manufactured goods. Its foundation, which took place in a geographically strategic position, allowed the Etruscans to establish profitable trade and at the same time to defend the territory from possible incursions. In the 1st century BC it became a Roman colony; around 600 it was subjugated by the Lombards and became the main port of the Tyrrhenian Sea used for trade with Sardinia, Corsica, France and Spain. The 11th century marked one of the most flourishing periods for the city. Pisa became one of the four Maritime Republics, together with Amalfi, Venice and Genoa; its port attracted merchants from all over the Mediterranean, quickly developing a sort of absolute dominion over the entire western maritime area. The buildings for which the city is famous throughout the world today date back to the years between the 11th and 12th centuries: the Cathedral and the Leaning Tower. The accumulated wealth allowed the Pisan fleet to undertake a series of successful maritime enterprises, brought to completion with the foundation of colonies in North Africa, southern Spain and on the southern coasts of Asia Minor. With the Crusade led by Archbishop Daiberto, the city expanded and established its own commercial colonies in the Middle East, thus establishing important trade relations with the Byzantine Empire and the entire Islamic world. From the period of the colonies, in addition to economic development, a strong cultural and artistic contamination arose. The second half of the 12th century marked an expansion within the same region. The years of economic splendor were accompanied by an artistic development linked to the name of Nicola Pisano, Giovanni Pisano and Arnolfo di Cambio; in the field of mathematics, Leonardo Fibonacci and his Indian positional number system are remembered. Little by little, however, the economic development of the Tuscan Maritime Republic began to arouse envy and jealousy on the part of the rival Republics. The rivalry culminates in the naval battle of Meloria, fought against Genoa in 1284, in the waters in front of the Pisan port. Thus begins the decline and the loss of supremacy over the sea. The period of splendor is followed by important political changes: the merchant class, becoming increasingly powerful, manages to introduce the figure of the Captain of the People, replacing the consul. The people rebel and impose on the legislative councils, until then led exclusively by the nobles, councils formed by their representatives with the task of ratifying the laws.