Similar subterranean rooms are found among ruins in the North-American South-West, indicating uses by the ancient peoples of the region including the ancestral Puebloans, the Mogollon, and the Hohokam. Those used by the ancient Pueblos of the Pueblo I Period and following, designated by the Pecos Classification system developed by archaeologists, were usually round and evolved from simpler pit-houses. For the Ancestral Puebloans, these rooms are believed to have had a variety of functions, including domestic residence along with social and ceremonial purposes.