The document summarizes the expansion of Christian kingdoms in the Iberian Peninsula between the 11th and 12th centuries as the Taifa kingdoms fragmented. Castile conquered territories south of the Duero River under Ferdinand I and his son Alfonso VI captured Toledo. Portugal gained independence from Castile in 1139 under its first king Afonso I. Aragon also expanded as King Alfonso I conquered Zaragoza. The new territories were conquered militarily by the Christian armies and then granted by the kings to vassals like nobles and monks, with free peasants receiving settlement letters granting them freedoms and tax exemptions.