Two early chronological periods of the early Puebloans or Anasazi - 100-500 AD, followed by the Modified Basket Maker period, 500-700; They lived people in the Four Corners area (northwestern New Mexico, southwestern Colorado, southeastern Utah, and northeastern Arizona) of the U.S. The origin of the Basket Maker Indians is not known, but it is evident that when they first settled in the area they were already excellent basket weavers and that they were supplementing hunting and wild-seed gathering with the cultivation of maize and pumpkins. They lived either in caves or out in the open in shelters constructed of a masonry of poles and adobe mud. Both caves and houses contained special pits, often roofed over, that were used for food storage. The Basket Makers were among the first village agricultural societies in the Southwest. Three Basketmaker stages were recognized at the 1927 Pecos Conference of Southwesternists: Basketmaker I (hypothetical), Basketmaker II (1--450 AD) which was a large base camp and widely scattered seasonal camps where the preferred container was the basket, and Basketmaker III (450--700/750) in which there were small villages of pit houses in well-watered valley bottoms. Specialized structures such as wattle-and-daub storage bins and large rooms for communal activity (possibly early kivas) also began to occur more frequently in the latter stage.