According to legend, the town was founded by the son of Aeneas, a certain Ascanio, or by the son of Hercules and Araxe, Tusco.
In reality, the area was inhabited since the Paleolithic, as evidenced by the numerous finds found, according to the reconstructions there were large settlements already in the Copper and Ancient Bronze Ages.
A great growth of the settlements occurred in the Etruscan era, when a large village was founded, starting from the eighth century BC the acropolis stood on Colle San Pietro, the strategic position of the town made it one of the main centers, and one of the most important cities of the Lucumonia of Tarquinia.
Over the centuries the city was incorporated into the possessions of the Roman Empire, in this period Tuscania experienced a long period of positivity, trade grew and activities flourished, it became a municipium in 88 BC, with the fall of the Roman Empire. ‘West the town suffered the incursions of the barbarians, then became a domain of the Heruli, the Goths and the Lombards, in 569 the city was conquered by the troops of Charlemagne and then ceded to the Papal States.
Having become a free municipality in 1100, the city managed to gain control over the nearby cities, such as Canino, Cellere, Montalto di Castro etc …
Following the struggles between the Guelphs and Ghibellines, the fate of the city worsened, until it was placed under the control of Viterbo, elevated, in 1192 to the Episcopal See.