The varying results of incorporation on the survival of groups such as bands, tribes, chiefdoms and mercantile states can be explained by applying the historical process to the American conquest of the Southwest. The American Southwest (the region covered by Arizona, New Mexico, parts of Texas, California, Utah, Nevada, and Colorado) was occupied by four aboriginal groups (Apaches, Navajos, Comanches, and Pueblos). In addition to the aboriginal inhabitants, there were two successive waves of invaders (Spaniards and Americans). The conquest began with the opening of the Santa Fe Trail in 1822 and concluded with the formal annexation of the region in 1848. The effects of the conquest on the Comanche, Apache, Navajo, Pueblo, and Hispanos were varying degrees of cultural persistence, demographic survival, political centralization, ecological adaptation, and external utility of resources. The American conquest of the Southwest produced several irreversible changes which included all three band societies becoming tribes; the Santa Fe Trail trade was a major factor in feudalization of New Mexico, intensifying relations between the Hispanic elite and poor. The Southwest (New Mexico and Arizona primarily) remained relatively marginal to the American economy making it an effective preserve for a variety of ethnic groups. (ERB)