Excavation on the Dadiwan site revealed the developmental course of the Neolithic culture in the eastern Gansu region during 7800—4800BP, as well as the evolutionary trace of the pattern of a prehistoric settlement going through 3000 years. The first phase of the site belongs to the Laoguantai culture, and the settlement falls into the type of scattered terraces. The second phase is of the early Yangshao culture; the settlement represents the moat-surrounded terrace pattern, an outstanding change from a single center to multiple centers. The fourth phase consists of remains of the late Yangshao culture; the settlement became a large-scale center in a mountainous district. Its main body occupies an area of 500,000 sq m; a large-sized hall-type building stands at the center of the district ; and living quarters are densely distributed in the surrounding areas. The changes of the site in the four phases reflect that the Dadiwan settlement went through the evolutionary course from the smaller to the larger, from river side terraces to a mountainous district, and from a single village to a central settlement. In the period of Yangshao culture, agriculture developed swiftly, the population increased sharply, and the settlement reached the stage of great prosperity. But owing to the over-reclamation of land, the ecological environments gradually worsened, which finally led to the decline of the settlement.
