This article revises the spatial and temporal boundaries of the Casas Grandes tradition associated with northwest Chihuahua, Mexico, based on new data collected in neighboring northeastern Sonora. The Casas Grandes tradition attained its greatest extent during the Medio period (AD 1200–1450/1500) followed by a dramatic demographic and political collapse. Hunter-gatherer groups subsequently occupied most of northwest Chihuahua. Data from the Fronteras Valley, Sonora, presents an alternative scenario, with a clear pattern of cultural continuity from the eleventh century to the colonial period in which sedentary farmers occupied the same landscapes and occasionally the same villages. These observations contribute to our understanding of the spread and subsequent demise of the Casas Grandes tradition in hinterland regions. For the Fronteras Valley, we infer that immigrant groups originally introduced Casas Grandes traditions and that uneven participation in a suite of shared religious beliefs and practices was common to all the hinterlands.
