When the Contessa Matilda died in 1115, the people of Florence had already constituted, to all the effects a Common one. The numerous ones privilege from granted she and the events in which the Community fiorentina had carried out a main role in the fight against the emperor, had induced people to organize themselves independently and to undertake the action heading to weaken the imperial power.
It was therefore unavoidable that in 1125, to the dead women of the last emperor of the franconiana dynasty, Enrico V, i Fiorentini decided of attacare and destroying Fiesole, the near city avails again. To the end the two counties were joined and remained separate entities only to ecclesiastical level, with Fiesole that has maintained its diocese. The first mention of a Common one officially constituted given 1138, when to a reunion of from Tuscany cities it was decided to constitute an alloy, for fear that Enrico the fierce one, than had them previously overwhelmed, was elect Emperor.
To that time the Community had of the religious and secular representatives, with three dominant social groups: the noble ones, group to you in consorterie, the traders and the soldiers to horse, the base of the army. Even if the noble ones stopped the greater part of the power, in the twelfth century, were the traders the main authors of the development of the city.
The increase of the traders in the second half of the century, therefore as the commerce with the distant countries was intensified and transformò in one new and much richer source than accumulation of understood them.
The extended commerce and the inseparable companion, the credit, were the base of the economic and demographic expansion of the city.