sentences:  The approach to the site was protected by steep hillsides, augmented by a high platform topped by sheer walls.The fortification of the city took place between AD 680 and 810, and may have been motivated by the military catastrophe that overtook nearby Río Azul at the end of the Early Classic period (c. AD 600).It is likely that Kinal superseded Río Azul as the primary centre in the region and adopted the administrative functions that were formerly the preserve of that city.