The trickle of convenientiae that began in the 1020s and continued through the 1040s became a flood from 1050 on. Fewer than 50 survive from the first half of the eleventh century; over 600 are preserved from the second half. Counts, viscounts, bishops, abbots, clerks, castellans, and peasants from every county all took advantage of the new form to record their agreements. These multiplying agreements are not isolated from one another; rather, they overlap, forming networks and structures. A single agreement between two individuals is of only limited import. Hundreds of agreements within a community begin to shape the social order.

Since the richest concentration of agreements for this period concerns castle holding, the development of structures based on written agreements is most easily seen in a consideration of that subject. What was a castle in eleventh- and twelfth-century Catalonia? As research into the phenomenon of concentration of habitats in fortified sites on the Italian peninsula (incastellamento) has made clear, the castle of the tenth to twelfth centuries was much more than a fortified site or building. It served administrative, political, economic, military, and even symbolic functions that varied from region to region.