The two regions that developed the most aggressive and confident nationalist movements in Spain – the Basque country and Catalonia – had many features in common which set them apart from the rest of Iberia. Both enjoyed a relatively prosperous agricultural base characterized by medium-sized landholdings, security of tenure, polyculture, dispersed residential patterns and an inheritance system that transmitted the rural farmstead intact to only one heir. Both were in direct geographical contact with Europe and developed powerful mercantile classes which were enthusiastic recipients of European technical and ideological innovations. Finally, during the nineteenth century both experienced an industrial take-off. In Catalonia and the Basque country industrialization was managed by a native industrial bourgeoisie and generated a politically militant proletariat of mixed regional origins. Despite these similarities, however, Basque and Catalan nationalism are very different political creatures.

The Basque country – or Euskalherria – runs along the Bay of Biscay. It extends from Bayonne in the northeast to just west of Bilbao and, straddling both sides of the Pyrenees, cuts inland some 200 km. This hilly, luxuriant region, whose densely green appearance belies an infertile soil, is composed of seven provinces: Guipúzcoa (Gipuzkoa), Vizcaya (Bizkaia), Alava (Araba), Soule (Zuberoa), Basse-Navarre (Baxanabarra) and Labourd (Lapurdi). Covering slightly more than 20,000 km, the region contains 2,376,134 inhabitants (1974 census) of which about 90% live in the Spanish Basque country and the remainder in France. Divided politically between two states, Euskalherria is divided geographically by two massive mountain ranges.