West Iberian is a branch of the Ibero-Romance languages that includes the Castilian languages (Spanish, Judaeo-Spanish), Astur-Leonese (Asturian, Leonese, Mirandese, Extremaduran (sometimes), Cantabrian), Navarro-Aragonese and the descendants of Galician-Portuguese.
Until a few centuries ago, they formed a dialect continuum covering the western, central and southern parts of the Iberian Peninsula—excepting the Basque and Catalan-speaking territories. This is still the situation in a few regions, particularly in the northern part of the peninsula, but due to the differing sociopolitical histories of these languages (independence of Portugal since the early 12th century, unification of Spain in the late 15th century under the Catholic Monarchs, who privileged Castilian Spanish over the other Iberian languages), Spanish and Portuguese have tended to overtake and to a large extent absorb their sister languages while they kept diverging from each other.
