 From the 15th century , changes to the areas surrounding Santa María de Óvila initiated a slow decline . Civil wars depopulated the villages of the upper Tagus valley . The monastery 's land holdings passed one by one into the hands of the new regional aristocracy : first the Count of <unk> , followed by Rui Gomes da Silva , Duke of Pastrana , and the Spanish Army . Neighbors looted more lands . 
