Barbarano is a medieval village on a plateau of volcanic rock at the intersection of two rivers, the stream Biedano and its tributary, as was the preferred practice for Etruscan settlements. In fact, here were found a necropolis of San Giuliano and the Marturanum settlement dating back to the period between the eighth and sixth centuries BC.
With the arrival of the Romans who defeated Veii in 396 BC, the center continued to be active because it was on an important route from Via Clodia that connected Rome with Etruria.
The San Giuliano site was then inhabited until the eleventh century AD when the population moved to the current Barbarano. The promontory of Barbarano is in fact the most defensible and in the Middle Ages was ideal for the people seeking shelter in a fortified castle from the incursions of Barbarians and Saracens.
By the presence of the remains of a Lombard tower, Torre di Re Desiderio, it is clear that in 771 the Lombards were settled and looking for ways to counter the advance of Charlemagne.
From the plaque on the Santa Maria Assunta church, which bears the date of 1280, during the vacancy of the papacy after the death of Pope Nicholas III, it follows that Barbarano was part of the Roman-Lombard Duchy that entered the church by donation of Liutprando in 728.
The country became a bishopric and appears the first time as such in a 1188 document in which Pope Celestine III gives it to the City of Viterbo. Barbarano then appears in the possessions of Viterbo directly besides the church.
During the fourteenth and fifteenth centuries it belonged to several distinguished noblemen–
Until the fifteenth century the history of the village is characterized by struggles for dominance of the fiefdom between the Lords of Farolfo of Viterbo and Di Vico, Prefect of Rome.
From 1283 to the nineteenth century, the town remained subject to the feudal law of Rome, and among the families that governed it from where its name of Barbarano Romano arose. The several families included the Anguillara, the Orsini and the Borgias.