Strabo cites Ephorus's belief that there were Celts in the Iberian peninsula as far as Cadiz. The material culture of the north-western regions of the Iberian Peninsula showed continuity from the end of the Bronze Age (c. 9th century BC) until it was subsumed by Roman culture (c. 1st century BC). It is associated with the Celtic tribal groups the Gallaecians and the Astures. The population predominantly practiced transhumant cattle-herding, protected by a warrior elite, similar to those in other areas of Atlantic Europe, centered in the hill-forts, locally termed "castros", that controlled small grazing territories. Settlements of circular huts survived until Roman times across the north of Iberia, from Northern Portugal, Asturias and Galicia through Cantabria and northern Leon to the Ebro River.