ABSTRACT
Archaeological excavations at the Schroeder and La Atalaya sites in Durango and in a number of sites in western Zacatecas have produced considerable chronological data. Firm archaeological evidence for the relation of the two sequences has been obtained. The Suchil branch is early and in terms of Mesoamerican archaeology belongs primarily in the Middle and Late Classic period, whereas the Guadiana branch is later and belongs primarily to the Postclassic period. In general terms a putative founding date for Alta Vista in the sixth century A.D. is acceptable although later than suspected in relation to other archaeological data. Ceramic types presented in refuse deposit were those of the Alta Vista phase; indeed the "Palace" structure appears to have been built during the period of expansion and reconstruction of the site between A.D. 800 and 850. The initial date of the earliest Ayala phase must lie between ca, A.D. 850 and 900, say A.D. 875.
