The first evidence of this church comes from two papers from the years 949 and 1011; at this time the church appears to have been dedicated to Saint John the Baptist.
The founding document of Badia a Elmi from 1034 shows that the church was already dedicated to Santa Maria Assunta. The territory of the parish was often disputed between the counts of Cadolingi and the bishops of Volterra, who already had jurisdiction. From the end of the twelfth century, information about this parish began to accumulate, news reporting both the progress of some works and the names of the rulers. At the base of the bell tower there is an inscription that reads: + REMOTA FUIT H PLEBS A M CXC IN ITA FACTA TEMPORE ILD PLE; There is evidence that in 1190, at the behest of the then priest Ildebrando, the title of a previous church that was located nearby was transferred to this building.
The priest Ildebrando was the central figure in the life of this building, so much so that he was still the priest in 1250. During his plebanate, all work on the new church was carried out, which lasted at least 50 years; The inauguration of the church took place in 1238, as an inscription on the facade reports; but that's not all, the priest also played an important role in the civil life of the area, so much so that he was appointed as a judge in various disputes that broke out in the area.
Source: Wikipedia (Italian)