The pithouse represents the beginnings of a settled way of life based on agri­culture. Its basic features were a living room, squar­ish in shape and sunk a few feet into the ground, four main timbers at the corners to support the roof, a firepit with an air deflector, an antechamber, which might contain storage bins or pits, and a si­papu. Sipapu is a Hopi word and is a small hole or indentation in the floor of kivas used by the Ancient Pueblo Peoples and modern-day Puebloans. It symbolizes the portal through which their ancient ancestors first emerged to enter the present world. Pithouses evolved into the kivas of later times. In Mesa Verde, the people lived in this type of dwelling from about 550 to 750 AD.