The advance of the northern frontier of the viceroyalty of New Spain in the sixteenth century led to the founding in 1567 of Santa Bárbara, located in what is now southern Chihuahua on one of the tributaries of the Conchos River, which flowed northward to the Rio Grande. Santa Bárbara thus became the primary base for the exploration and colonization of New Mexico in the remaining decades of the century. On June 5, 1581, three Franciscans-Agustín Rodríguez, Francisco López, and Juan de Santa María-left Santa Bárbara to explore missionary possibilities in the country to the north. They were accompanied by an armed escort of eight soldiers under the command of Francisco Sánchez (also called Chamuscado), nineteen Indian servants, ninety horses, and 600 head of stock. The party descended the Conchos River and at its junction with the Rio Grande entered the territory of the Cabris nation, described as a handsome, well-built, intelligent people, who gave the Spaniards food and told them that some years before four Christians had passed through the area-no doubt Cabeza de Vaca and his companions. The Indians added that there were more, much larger settlements upstream.
The Rodríguez-Sánchez expedition continued along the west bank of the Rio Grande through the area of present El Paso and in August 1581 arrived at the Piro and Tigua pueblos of New Mexico. On August 21 the party took formal possession of the land for the king of Spain. For the remainder of the year it explored extensively in all directions, covering much of the same territory viewed by Francisco Vásquez de Coronado forty years before. In the meantime, Fray Santa María had ill-advisedly set out on his own to report to the viceroy and was killed by Indians in September 1581, though his companions did not learn of his fate until sometime later.
In early 1582 Sánchez and his men discussed the desirability of returning to Santa Bárbara to report to the viceroy, but the two Franciscans, Fray Rodríguez and Fray López, announced their intention of pursuing further their missionary endeavors in New Mexico. They did not heed Sánchez's warnings of the great dangers involved and on January 31, 1582, stayed behind when the little band returned to Santa Bárbara. The aged Sánchez died before reaching the northern outpost, but the rest of the party arrived there on April 15, 1582, after an absence of almost eleven months. Glowing accounts of great wealth in New Mexico, together with the concern about the safety of the friars, led to preparations for another expedition to the new land. Thus, the discovery by the Rodríguez-Sánchez expedition of a new route to New Mexico laid the foundation for the introduction of Spanish civilization in what is now the American Southwest.