A kiva is a space used by Puebloans for rites and political meetings, many of them associated with the kachina belief system. Among the modern Hopi and most other Pueblo peoples, "kiva" means a large room that is circular and underground, and used for spiritual ceremonies.
Similar subterranean rooms are found among ruins in the Southwestern United States, 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.
During the late 8th century, Mesa Verdeans started building square pit structures that archeologists call protokivas. They were typically deep and in diameter. By the mid-10th and early 11th centuries, these had evolved into smaller circular structures called kivas, which were usually across. Mesa Verde-style kivas included a feature from earlier times called a sipapu, which is a hole dug in the north of the chamber that is thought to represent the Ancestral Puebloans' place of emergence from the underworld.
When designating an ancient room as a kiva, archaeologists make assumptions about the room's original functions and how those functions may be similar to or differ from kivas used in modern practice. The kachina belief system appears to have emerged in the South-West around A.D. 1250, while kiva-like structures occurred much earlier. This suggests that the room's older functions may have been changed or adapted to suit the new religious practice.
As cultural changes occurred, particularly during the Pueblo III period between 1150 and 1300, kivas continued to have a prominent place in the community. However, some kivas were built above ground.