The family could trace its origins back to around AD 984 and took its name from one of its oldest feudal possessions - "Castrum Farneti". There has been some debate as to the origins of the name Farnesi/Farnese. Some suggest that it derives from the vernacular name for an oak found in the region, the Farnia ("Quercus robur"), but others have held that the name owes its origins to the Fara, a term of Lombard origin used to denote a particular social group.