Aztec Obsidian Study Uncovers Complex Ancient Trade Networks
The study, published in the Proceedings of the National Academy of Sciences, analyzed 788 obsidian artifacts from the Templo Mayor, revealing that while the Mexica primarily relied on green obsidian from the Sierra de Pachuca, they also imported the material from at least seven other regions, including Ucareo in the Purepecha territory of West Mexico. This finding suggests the Mexica economy depended not only on direct control but also on extensive long-distance trade with neighboring polities.
"Although the Mexicas preferred green obsidian, the high diversity of obsidian types, mainly in the form of non-ritual artifacts, suggests that obsidian tools from multiple sources reached the capital of the Empire through market instead of direct acquisition in the outcrop," said lead author Diego Matadamas-Gomora, a PhD candidate in Tulane's Department of Anthropology. "By studying where this material came from, we can explore the movement of goods across Mesoamerica."
Nearly 90% of the artifacts in the study were made from Sierra de Pachuca obsidian, which was prized for its green hue and symbolic connection to the mythical city of Tollan. This type of obsidian dominated ceremonial offerings, including miniature weapons, jewelry, and inlays for sculptures, emphasizing its ritual importance. However, smaller quantities of obsidian from other sources, such as Otumba, Tulancingo, and El Paraiso, were more commonly found in everyday tools and construction fill, indicating these materials were traded through local markets and accessible to the general population.
The study also highlighted a shift in obsidian sourcing over time. In the early phases of Tenochtitlan's history, obsidian for both ritual and everyday use came from a broader range of sources. However, following the consolidation of Mexica power around 1430 CE, the supply for ritual objects became almost exclusively limited to the Sierra de Pachuca, reflecting growing religious standardization and centralized control.
"This kind of compositional analysis allows us to trace how imperial expansion, political alliances and trade networks evolved over time," Matadamas-Gomora said.
The research, conducted in collaboration with Mexico's Proyecto Templo Mayor of the National Institute of Anthropology and History (INAH), used portable X-ray fluorescence (pXRF) to analyze the geochemical composition of the artifacts, providing a non-destructive way to trace their origins and trade paths.
"This work not only highlights the Mexica Empire's reach and complexity but also demonstrates how the archaeological sciences can be leveraged to study ancient objects and what they can tell us about past cultural practices," said study co-author Jason Nesbitt, an associate professor in Tulane's Anthropology Department.
Research Report:Compositional analysis of obsidian artifacts from the Templo Mayor of Tenochtitlan, capital of the Mexica (Aztec) Empire
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