of the most prominent examples of the Toltec material culture at the site include pyramids, ball-courts, and the Atalantean warrior sculptures on top of Pyramid B. Various civic buildings surrounding a central plaza are especially distinctive, as excavations show the use of columns inside these buildings and in surrounding colonnades. One of these buildings, known as Building 3, is argued to have been a symbolically powerful building for the Toltec due to its reference in architecture to the historic and mythic homes of the people's ancestors. The physical layout of the broader plaza also partakes in referencing a shared past; its sunken colonnaded hall units are incredibly similar to those at cities of Tula's ancestral peoples. Importantly, these halls are known to have served as places to engage with both regional and long-distance trade networks and were possibly also used for diplomatic relations, suggesting that Tula Grande used these structures for a similar end. To that point, imported goods at Tula Grande shows that the Toltecs indeed interacted commercially with sites throughout Mesoamerica; shared ceramic and ritual figurine styles between Tula and regions such as Socunusco supplement this idea. 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. History of research One of the earliest historical mentions of Toltecs was in the 16th century by the Dominican friar Diego Durán, who was best known for being one of the first westerners to study the history of Mesoamerica. Durán's work remains relevant to Mesoamerican societies, and based on his findings Durán claims that the Toltecs were disciples of the "High Priest Topiltzin." Topiltzin and his disciples were said to have preached and performed miracles. "Astonished, the people called these men Toltecs," which Duran says, "means Masters, or Men Wise in Some Craft." Duran speculated that this Topilzin may have been the Thomas