The development of the field of historical archaeology in Mexico has made many advances since the inception, in effect, of its practice there in the 1960s. The roots of historical archaeology in the Central Mexican Symbiotic Region (CMSR) in general and in the Basin of Mexico in particular are discussed. Specific case studies illustrating some of the Historical Archaeology that has been done in the CMSR are referenced with particular note of some of the diagnostic materials that have been valuable to the studies. The value of these studies to the record of post-Conquest Mexico is noted as are the prospects for continued research in the area.

Obsidian and ceramic artifacts from the Otumba project were analyzed by instrumental neutron-activation analysis. Sources for the obsidian were determined by comparison to a databank of Central Mexican source analyses. Ceramic sources were determined by comparison to a series of reference groups from the Basin of Mexico and by comparison with raw material samples. Obsidian from the lapidary workshop (Operation 11) comes predominantly from the Otumba and Pachuca sources. There is also an unknown compositional profile present among the artifacts. This profile may derive from a not-yet-sampled flow within one of several nearby obsidian-source areas, such as Otumba or Paredon. The majority of Otumba ceramics fall into a large group derived from clays of the Teotihuacan-valley alluvium. Aztec II Black-on-Orange and red-ware samples come from other sources in the eastern basin. Ceramics from sites along the trade route leading northeast toward Tulancingo include figurines derived from Otumba, figurines probably made locally near Tepeapulco and Tulancingo, and long-handle censers probably made in the latter two locations.

Otumba is one of a few Late Aztec-period city-states in the Basin of Mexico whose central city or town is not obscured by post-Conquest occupation. Long-term research there began in the early 1960s, with more recent fieldwork between 1987 and 1989, and has been complemented by intensive laboratory and technical analyses that are still underway. Traditional typological analyses have been aided by neutron activation analyses providing strong evidence of economic linkages between the Otumba city-state and raw material sources, as well as evidence of tribute and market distribution channels for finished products within and outside the Otumba city-state.

The Aztec city-state of Otumba is the focus of a long-term project of archaeological investigation. Analysis of surface and excavated ceramics and obsidian-hydration dates for the capital—Otumba—indicate a dispersed Mazapan occupation, a scattered early Aztec (Aztec II) occupation, and an intense Late Aztec (Aztec III) and Early Colonial (Aztec III/IV) occupation. In the paper we incorporate recent radiocarbon dates to refine the local late Postclassic chronology. A cluster of hydration dates suggests the early (Mazapan) occupation starts ca. a.d. 900. Aztec II ceramics, which are widely distributed in surface artifact collections, may begin as early as a.d. 1200 and continue until a.d. 1400, overlapping Aztec III ceramics, which we have dated from a.d. 1350 ± 50 to 1521 and later. Otumba continued to have a substantial occupation until ca. a.d. 1600/1620 in the early seventeenth century, when most of the Aztec town was abandoned.

Blanton ’s use of a hypothesis of warfare among Early Post- Teotihuacan sociocultural entities of the Basin of Mexico to account for selective reoccupation following the end of Teotihuacan is based ultimately on a conceptualization of a dichotomy between a peaceful Classic period and a warlike Postclassic period. Except for unoccupied areas between local concentrations of Early Toltec sites there are no data to support the warfare hypothesis. Through a presentation of available Early Toltec settlement pattern data from the Basin of Mexico and a consideration of the sociocultural connections between Teotihuacan and the Early Toltec epi-Teotihuacan states, I support my earlier model which utilizes a tightly reasoned cultural ecological (sociocultural factors pais environmental features) framework to account for and predict the locations of concentrations of Early Toltec period sites. Continuity between Teotihuacan and the Early Toltec period sites is stressed.

The use of a hypothesis of conflict between Tula and Cholula by Parsons (1970) to account for settlement patterns and ceramics of the Toltec periods in the Texcoco region has resulted in the introduction of inconsistencies in the settlement interpretations of the preconquest Texcoco sequence. The Tula-Cholula Conflict Hypothesis is based on inadequate data and not supported. However, it is possible to interpret the settlement and ceramic changes of the Texcoco sequence using ecological and cultural factors suggested by Parsons for periods earlier than the Early Toltec. The correlations suggested by Parsons (1970) between the Codex Xolotl and the Early Toltec period rested in part on the use of the Tula-Cholula Conflict Hypothesis. With the elimination of this hypothesis, it is possible to correlate the 2 basic culture patterns of the Codex, as defined by Parsons, with terminal Late Toltec and Early Aztec. These correlations support Dibble"s original thirteenth century date for the early events depicted in the Codex Xolotl.

Documentary data of the sixteenth century indicate the manufacture of ceramic vessels for salt-making and trade. Texcoco Fabric-marked pottery is the archaeological manifestation of these vessels. Use of a special ware is related to increased salt-making in the Aztec period. Implications of this for the economic integration of Central Mexico are mentioned.

Recent archaeological and ethnographic research has made known the pre-Conquest and contemporary settlement patterns of the Teotihuacán Valley. Similar data for the intervening post-Conquest period are not available. Most archaeologists have restricted their research to the pre-Conquest period, and the documents do not contain pertinent detailed information on settlement patterns.

To resolve this problem I propose the application of archaeological methodology to sites located and identified through ethnohistoric research. My preliminary results in the area southeast of Otumba suggest that the method is feasible and productive.

I also explore the theoretical implications of the data recovered from dated archaeological deposits for which the relevant sociocultural factors are known.

An examination of reports by Tylor (1861), Holmes (1900, 1919), and Spence and Parsons (1967) describing obsidian mines near Cerro de las Navajas in southern Hidalgo indicates that not one but three mine groups have been visited and described.

An examination of the data used to support Nunley’s hypothesis (1967) that Texcoco Fabric-marked pottery vessels functioned as flowerpots to adapt chinampa agriculture to saline Lake Texcoco does not confirm his conclusions. The distribution of the ware and tlateles coincides not with chinampa agriculture but with salt-producing communities of the 16th century. Aboriginal salt-making produced large mounds of washed or leached soils which are the tlateles. Texcoco Fabric-marked ware is suited for the rapid heating of saline solutions. It is concluded that the sherds and the tlateles are the archaeological remains of Aztec salt-making activities.