These two cultural groups, the Mogollon in southwestern and southern New Mexico, whose roots extend back through the ancestral Cochise to before 6000 B.C., and the Anasazi in the Four Corners region of northwestern New Mexico, probably developed independently during the early years. From about 500 A.D., however, there is increasing evidence of trade relationships and eventual fusion of traits. Other groups to the west, such as the Hohokam of Arizona, were sources of cultural influence on the indigenous people of New Mexico. In the Mogollon and San Juan Anasazi heartlands and in the Rio Grande Valley of central New Mexico, a pattern of village life with elaboration of social and religious organization emerged from the relatively simple cultures of the early years. Villages began to assume organized form, dwellings were combined in rows of adobe and stone structures containing a number of contiguous rooms, and subterranean ceremonial chambers or _kivas_ assumed larger and more specialized architectural distinctiveness from the ancestral pit-house dwellings. In the Mogollon area, the characteristic brownware pottery of the Mogollons was used side by side with decorated black-on-white pottery of Anasazi origin. The bow and arrow slowly replaced the less efficient _atlatl_ and dart. The significance of these early stages in the evolution of the Pueblo Culture in the San Juan and upper Rio Grande areas is indicated by their designation as the Developmental Pueblo period (Pueblo I and II). [Illustration: (_Photograph of museum diorama courtesy of the Chicago Natural History Museum_) Figure 4. Mogollon pit-house village of the period 200 B.C.] The climax of these developments occurred in the interval between 1050 and 1300 A.D. in the Classic or Great Pueblo period (Pueblo III). Among the most impressive manifestations of this period are large stone-masonry apartment houses, some rising to five stories in height and housing hundreds of people. Dwellings of this type are highlights of several well-known tourist attractions, among which are the cliff dwellings of Mesa Verde in southwestern Colorado and the monumental ruins of Pueblo Bonito in Chaco Canyon (fig. 5), both products of the ingenuity of the Anasazi Indians.