Before the arrival of the Spanish, two indigenous groups dominated the areas, the Guachichils and the Zacatecos. The Zacatecos spoke a language similar to Nahuatl, and were agricultural. In the 16th century, Jerez lay on the road that Cristobal de Oñate took while he was looking for gold. He found it southwest of the city of Zacatecas. The land of this area was granted to Captain Pedro Carrillo Dávila for his role in the Conquest. He was followed by missionaries, which worked to convert the indigenous of the area until the end of the 16th century. The original churches of the town were dedicated to Ildefonsus and Saint Dominic . Oral history states the town was founded in 1536 to defend the road between Guadalajara and Zacatecas from indigenous attacks, but written records officially place the founding in 1570.