The foundation of the town is attributed to the Chichimecas, in 116 or 1168 A.D. Historical records show that the town was dominated by the Toltecs and the Tepanecas as well as the Aztecs. The Aztecs were the last to take control, this region was named Teotlalpan, after Chimalpopoca conquered the area in 1415. Tequixquiac remained in the Tepaneca district of the Aztec Empire under the authority of the lord of Tacuba, paying tribute to him at Hueypoxtla. The town kept its chiefs, now loyal to the Aztecs, one of the last of which was Acalmiztli, who supposedly was very respected among his subjects. The inhabitants of pre-Conquest Tequixquiac were known for their strict honor code and being advanced in medicine, education, architecture, and civil engineering.