Saltillo is the capital and largest city of the northeastern Mexican state of Coahuila and is also the municipal seat of the municipality of the same name. Mexico City, Monterrey, and Saltillo are all connected by a major railroad and highway. As of a 2020 census, Saltillo had a population of 879,958 people, while the population of its metropolitan area was 1,031,779, making Saltillo the largest city in the state of Coahuila, and the 14th most populated metropolitan area in the country.

The Chichimeca War (1550–90) was a military conflict between the Spanish Empire and the Chichimeca Confederation established in the territories today known as the Central Mexican Plateau, called by the Conquistadores La Gran Chichimeca. The epicenter of the hostilities was the region now called the Bajío. The Chichimeca War is recorded as the longest and most expensive military campaign confronting the Spanish Empire and indigenous people in Aridoamerica. The forty-year conflict was settled through several peace treaties driven by the Spaniards which led to the pacification and, ultimately, the streamlined integration of the native populations into the New Spain society.