A number of disparate onomastic phenomena occurring in northwestern Iberia have long puzzled scholars: the abundance of Arabic personal names in early medieval Christian communities, often fossilised as place–names; the extraordinarily profuse Romance toponym Quintana; and a surprisingly high number of hypothetical Amazigh (i.e. Berber) demonyms. In this paper we argue that these seemingly disparate onomastic phenomena can all be explained if it is accepted that following the Islamic invasion of Iberia in 711, the Amazigh settlers of the Northwest were at least partially latinophone. The internal history of the Maghreb suggests this would have been the case at least in the sense of Latin as a lingua franca, a situation which the speed and superficiality of the Islamic conquest of said region would have been unlikely to have altered significantly. In this context, all of the puzzling onomastic elements encountered in the Northwest fall into place as the result of the conquest and settlement of a Romance– speaking region by Romance–speaking incomers bearing Arabic personal names but retaining their indigenous tribal affiliations and logically choosing to interact with the autochthonous population in the lan-guage they all shared.