In Central Mexico, the height of the classic period saw the ascendancy of Teotihuacán, which formed a military and commercial empire whose political influence stretched south into the Maya area as well as north. Teotihuacan, with a population of more than 150,000 people, had some of the largest pyramidal structures in the pre-Columbian Americas. After the collapse of Teotihuacán around 600 AD, competition ensued between several important political centers in central Mexico such as Xochicalco and Cholula. At this time, during the Epi-Classic, Nahua peoples began moving south into Mesoamerica from the North, and became politically and culturally dominant in central Mexico, as they displaced speakers of Oto-Manguean languages.