The early history of Teotihuacan is quite mysterious and the origin of its founders is uncertain. Around 300 BCE, people of the central and southeastern area of Mesoamerica began to gather into larger settlements. Teotihuacan was the largest urban center of Mesoamerica before the Aztecs, almost 1000 years prior to their epoch. The city was already in ruins by the time of the Aztecs. For many years, archaeologists believed it was built by the Toltec. This belief was based on colonial period texts, such as the Florentine Codex, which attributed the site to the Toltecs. However, the Nahuatl word "Toltec" generally means "craftsman of the highest level" and may not always refer to the Toltec civilization centered at Tula, Hidalgo. Since Toltec civilization flourished centuries after Teotihuacan, the people could not have been the city's founders.