 Among the municipalities formed were Tollocan, Tenancingo, Ocuilan, Calimaya and Tepemaxalco, the latter being the most important.The Matlatzinca lands were considered a corn producing region, and this may have been the main reason for the continued invasions from the epiclassical period, first by the Toltecs and subsequently by Chālcah (confederacies) in the 12th century.The region was divided into three Altepetls, two of which were prepared to remain independent and possibly associate with the Purépechas of Michoacán, but a third Altepetl (Tollocan), wanted an association with the Aztecs.