Thanks to word of mouth passed down over the centuries it is known that the production of terracotta in the area of Petroio actually dates as far back as the Etruscan period. This is further substantiated by the findings and fragments discovered at archaeological sites in the valley of the Trove Torrent and in the town itself. In actual fact, the first documents that bear witness to an organised activity of terracotta production date back to the Modernist period and in particular to the end of the 17th century. During a visit to the State of Siena in 1676-77,Bartolomeo Gherardini wrote the following about Petroio: "I am in this fortress of strange trades and workshops. There is a bookbinder, an ironmonger, a blacksmith, two farmhouses, a workshop where cups and pitchers are made from clay, and four other workshops where pots and roofs are made. There is also a builder, 16 artists and weavers. Thanks to the so-called potter's who make objects for various leaders, a little income enters the fortress. Trading at the nearby Val di Chiana and in the surrounding regions is possible thanks to the dye from madder plants, which is used by the potters for decorating their products.