central coast, however, seems never truly to have adopted agriculture. Because Sonora and much of the northwest does not share many of the cultural traits of that area, it is not considered part of Mesoamerica. Though evidence exists of trade between the peoples of Sonora and Mesoamerica, Guasave in Sinaloa is the most north-westerly point considered Mesoamerican.

Three archaeological cultures developed in the low, flat areas