Ancient Obsidian Reveals Aztec Empire’s Trade and Religion

Thanks to obsidian, archaeologists have uncovered new insights into how the ancient Mexica civilization, more widely known as the Aztecs, managed their economy and spiritual life through a far-reaching network of trade routes. A recent study by Tulane University in partnership with Mexico’s Proyecto Templo Mayor has traced the origins of nearly 800 ancient obsidian artifacts found at the heart of the former Aztec capital, shedding light on how trade and religion were closely tied in one of Mesoamerica’s most powerful empires.

The findings are based on chemical analysis of objects recovered from Templo Mayor, a major religious site in what is now Mexico City. The research marks the most extensive obsidian study ever conducted at the site. Experts used advanced techniques to determine where each piece of obsidian—an ancient form of volcanic glass—was originally mined.

According to the study, nearly 90% of the obsidian came from Sierra de Pachuca, a region known for its distinct green-colored glass. This type of obsidian was not only admired for its strength and beauty but also held deep spiritual value. It was associated with Tollan, a legendary city central to Mexica mythology.

The power of obsidian in Aztec and spiritual life

The dominance of green obsidian in sacred objects highlights how the Mexicas used trade to reinforce religious traditions and political control. Archaeologists found that this specific type of obsidian was used almost exclusively in ceremonial offerings. These included items such as small weapons, decorative jewelry, and sculptural pieces placed in sacred spaces.

Tulane doctoral student Diego Matadamas-Gomora, the study’s lead author, explained that the consistent use of green obsidian points to centralized oversight of religious materials. This suggests that the empire had tight control over what could be used in spiritual ceremonies, reinforcing its authority through material choices.

Interestingly, the study also found obsidian from at least seven other areas, including regions once ruled by rival groups such as the Purépecha. These materials were mostly used for everyday tools found in construction waste. This suggests that while ceremonial items were strictly regulated, common tools likely moved through more open, local trade markets.

Obsidian use evolved with the expansion of the empire

Researchers also observed changes in obsidian sourcing over time. In the early years of Tenochtitlan, around 1375 CE, a wider mix of obsidian sources appeared in both sacred and household items. But by the 1430s, after the Mexicas strengthened their control, green obsidian from Sierra de Pachuca became nearly exclusive in religious settings.

This shift indicates a growing effort by the empire to standardize rituals and solidify religious practices across its territories. The study shows that the Mexicas relied not only on military strength but also on strategic trade and cultural unity to maintain power.

The research was made possible through a collaboration between Tulane University and Mexico’s National Institute of Anthropology and History. Using non-invasive tools, scientists were able to identify the exact origins of ancient objects without damaging them.

Anthropology professor Jason Nesbitt, a co-author of the study, emphasized the value of modern technology in uncovering ancient practices. He noted that this work reveals the scale of the Mexica’s influence and highlights how closely trade, religion, and daily life were connected in pre-Columbian Mesoamerica.