The currency of Lucca was highly valued in Europe as a means of exchanges and trade. The Crusaders relied on Lucca’s coins to pay for whatever services they required (equipment, food, logistics, transportation, ransoms, fees, soldiers salaries, rights of passage etc.). You travelled the world with Lucca’s money in your pockets: like the US dollars today. Or should I better say like Euros today. Just for the record the name of the Lucca currency was "lira".
The privilege to mint (il privilegio della Zecca) was confirmed by Frederick Barbarossa and by Frederick II Hohenstaufen, and also by the Popes. When Pisa tried to counterfeit Lucca’s coins the Pope issued a terrifying "anathema" against the Pisani and brought them to order. The "mint" privilege was given to Lucca for the reliability of the people and for the "security" of the walls, and the "mint" was the foundation of the "money culture" that eventually resulted in Lucca being the city of some of the most powerful financial and merchant bankers of the 11th, 12th, 13th and 14th century.
Trading with the whole of Europe (buying wool from England, fish from France, silver and gold from Spain, selling silk, wool fabric, steel artefacts like swords and cutlery) through the centuries allowed the merchants of Lucca to gather considerable fortunes and the need to invest the money they accumulated. This brought them inevitably brought them into the field of money lending and, eventually, merchant banking and financial banking with the most powerful Royal families of Europe.
From Lorenzo Matteoli