The origin of the settlements in the Libarna valley goes back to the mid Iron age (6th-5th centuries BC), when an Etruscan emporium created in Genoa during the first half of the sixth century BC set up a trade route along the Scrivia valley towards the Po Valley and the transalpine areas. A Ligurians village stood on the castle hill to guard the route and was still active in the second Iron Age (3rd-2nd centuries BC.); the burial grounds extended in the valley along the banks of the Pieve stream. The proto-historic importance of the settlement is confirmed by the pre-Roman name (Libarna) of the Roman city, mentioned in several ancient sources, such as Pliny in the Itinerarium Antonini and Tabula Peutingeriana; it inherited the role and function as a strategic point along an important highroad (via Postumia) from the pre-Roman centre.
Libarna was originally developed due to its connection with the great Roman consular road and was a trading centre and as a place to stop for people and goods in transit along the highway connecting Genoa with Aquileia. Between the second and first centuries BC, after the via Postumia highroad (148 BC) was opened and being granted first with Latin then Roman citizenship led to creating a programmed urban planning scheme and its traces are still visible in the network of the urban layout, lying in the same direction as the Roman consular road. The first archaeological finds of the city of Libarna can be dated back to between the middle and end of the first century BC.