Epiclassic and early postclassic interaction in central Mexico as evidenced by decorated pottery

There has been debate and uncertainty on two important issues in the Basin of Mexico: the formation of Epiclassic city-states following Teotihuacan state collapse (ca. A.D. 650), and the nature of the subsequent Early Postclassic Tula state expansion. I evaluate the Basin as a case of regeneration of socio-political complexity using stylistic and compositional pottery analysis to examine patterns of interaction from the Epiclassic (ca. A.D. 600/650-850) through the Early Postclassic (ca. A.D. 850-1150). I selected representative specimens of temporally diagnostic pottery from the three large settlement clusters in the northwestern Basin (Tula and the Zumpango region), the northeastern Basin (Teotihuacan Valley), and the southeastern Basin (Cerro Portezuelo, the Ixtapalapa and Chalco regions) to assess: 1) participation in regional cultural complexes, 2) direct exchange or local production of particular pottery types, 3) regional variation in the production of pottery. For certain time periods, ceramic patterns among smaller settlements clusters were distinguished. The combination of chemical and attribute analysis provided a robust method for identifying regional variation in pottery. Chemical characterization using Instrumental Neutron Activation Analysis (INAA) was used to provide fine-scaled compositional reference groups to assess regional production and exchange. Stylistic and technological attributes were used to define highly visible decorative traditions that were easily copied and low visibility production steps that were learned. Teotihuacan withdrawal from the southeastern Basin prompted reorganization and adoption of a distinctive pottery complex. Epiclassic settlement patterns throughout the Basin were reorganized into nucleated settlement clusters with unoccupied areas between them. Results indicate regional participation in the Coyotlatelco pottery tradition and a strong pattern of consumption of locally produced pottery by settlement cluster. Tula underwent significant urban growth in the Early Postclassic, while the Basin was marked by a process of "ruralization" as the Epiclassic centers dispersed and settlements filled the previously unoccupied landscape. Tula expanded its influence into the Basin with varying degrees of integration. The closest settlements in the northwestern Basin acquired the most Tula-produced pottery. The Teotihuacan Valley and Cerro Portezuelo settlements consumed mostly locally produced Tula style pottery. The southeastern settlements were least connected to Tula and initiated interactions towards Puebla-Tlaxcala.