Additionally, surveys of Tula Grande have suggested the existence of an "extensive and highly specialized workshop-based obsidian industry," at the site that could have been one of the sources of the city's economic and political power, taking on Teotihuacan's previous role as the region's distributor. A survey done by Healan et al. recovered roughly 16,000 pieces of obsidian from the site's urban zone and over 25,000 from its surrounding residential areas. Tula's involvement in obsidian trade is also evidence for the city's interaction with another powerful city in the region, Chichén Itzá, as the vast majority of obsidian at both sites comes from the same two geological sources.
Additionally, surveys of Tula Grande have suggested the existence of an "extensive and highly specialized workshop-based obsidian industry," at the site that could have been one of the sources of the city's economic and political power, taking on Teotihuacan's previous role as the region's distributor. A survey done by Healan et al. recovered roughly 16,000 pieces of obsidian from the site's urban zone and over 25,000 from its surrounding residential areas Tula's involvement in obsidian trade is also evidence for the city's interaction with another powerful city in the region, Chichén Itzá, as the vast majority of obsidian at both sites comes from the same two geological sources.