In the localities of Lucigliano, Toro, Le Mozzete and San Giusto a Fortuna, numerous flint stone tools, such as spear points, scrapers, etc., have been found.
), of which only some enormous stones now remain visible, and the extraordinary discovery in the locality of Monti of a series of tombs excavated in the shape of wells organised like a proper necropolis (7th century B.C.).
The presence of a market for livestock favoured the passage and permanence of people in these places and developed in the inhabitants an attitude of exchange, confrontation and dialogue that will remain and grow stronger over time to the present day.
Moreover, the fact that they returned to live in Mugello, almost as if they wanted to breathe the air of their ancestors, and that they built villas and fortresses there, once they had consolidated their economic and political power, may lead one to believe that it is likely that the Medici were actually coal merchants in Campiano, a small hamlet in the hills, close to the plain of Cafaggiolo, where Cosimo il Vecchio later had the architect Michelozzo Michelozzi build his famous villa.
The village of San Piero a Sieve received a considerable boost in relation to the operosity of the Medici: it grew larger and gained a certain importance in the political framework of the Mugello, also marking an increase in population.
Precisely for this reason, a ‘hospitale’ was created in 1275 overlooking the piazza della Pieve, in the village, by ‘presbiter Gianbonus’, as can be seen from the written plaque left during construction.
The bridge, one of the oldest on this river, was built by the famous Florentine master masons: Niccolò di Ciardo, Francesco Carletti and Giovanni Mercati.
The journey between the two towns required at least two days' riding and included a stop with an exchange of horses at San Piero a Sieve, facilitating trade, commerce and business.
Evidence of the Florentine bankers' family's interest can be seen in the impulse they gave to a pottery factory in Cafaggiolo, with a furnace and farmhouse for the managers, which became very famous at the time, due to the quality and quantity of the product.
In San Piero, Bernadetto de' Medici, Lorenzo's cousin, also had some dwellings under Schifanoia, which are still recognisable today but have been altered several times and reduced to anonymity.
Towards the end of the 15th century, in connection with a momentary lack of interest on the part of the Medici in their possessions in Mugello, a period of decline began and in 1551 the League of Tagliaferro was also placed under the Vicariate of Scarperia.
With the fall of the Medici in the 17th century, the village of San Piero a Sieve also experienced a long period of socio-economic stagnation, also due to the passage of the Grand Duchy first to the Habsburg-Lorraine and then to the French with the conquest by Napoleon.
With the construction of the new road, very wide to allow the passage of all types of vehicles and completely flat, the old medieval bridge was also demolished and a much larger and more solid one rebuilt, also to resist the frequent flooding of the Sieve river.
For this reason, the Via Provinciale and the axis that joined it leading to Barberino di Mugello were later raised to form embankments to defend the lower part of the town from flooding.
Economically, San Piero saw a great rebirth at the end of the 19th century, when, with the construction of the railway station, the first trains arrived, favouring the circulation of people and goods.
In this regard, it can be said that, along the entire Florence-Faenza route, San Piero a Sieve was one of the most significant stations, to which the citizens of Barberino, Scarperia and Firenzuola belonged.