No archeological finds in this area date before the Postclassic period. However, Olmec era finds in neighboring Almoloya del Río indicate that there was human inhabitants here at least as early as 1300 BCE. Evidence of Teotihuacan settlement or influence was found in the same area. Most of the archeological finds are concentrated on what used to be the shores of a lake in this area and the Tetépetl Mountain. In the municipality proper, the remains of a population center called Teotenanco appear between 1050 and 1260 C. E. with constructions reminiscent of Teotihuacan. In the center is a ceremonial precinct that was probably the center of a local theocracy. The earliest known ethnic group here is the Matlatzincas. This area, along with the rest of the Toluca Valley, was conquered by Axayacatl and brought into the Aztec Empire in the 1470s.