Infanzones appear in written sources from tenth-century Northwestern Iberia as servants of the aristocracy, linked to their magnate patrons through ties of clientele and service. Recurring episodes of political instability in the 980s-1030s undermined traditional authority and customary social identities in the kingdom of Leon, which provided some opportunities for upward mobility. Infanzones took advantage of this chance for social ascent by redefining themselves as warriors and consolidating their position as local elites throughout the eleventh century, to the point of being finally recognized as a nobility of blood.