Agustín Ahumada y Villalón, Marqués de las Amarillas, the forty-second viceroy (1755–1760) of New Spain, was born in Spain, probably in the last years of the seventeenth century. Before his arrival in New Spain, he had been governor of Barcelona and lieutenant colonel of the Regiment of Royal Guards. Military experience in Italian campaigns had also earned him a measure of fame. He arrived in Mexico City at a critical juncture for Spanish Texas. Attempts to expand missionary enterprises beyond San Antonio had collapsed on the San Gabriel River, and the Franciscans had already redirected their missionary efforts toward the Lipan Apaches on the San Saba River. The new viceroy saw no reason to depart from that course. On April 29, 1756, Amarillas summoned Father Alonso Giraldo de Terreros, a veteran missionary, to a conference in Mexico City. When the two men met on May 9, the viceroy informed Terreros that his cousin, Pedro Romero de Terreros, was considering sponsorship of missions for the Apaches. The two priests worked out details, which were formalized by the viceroy. Subsequently a new presidio, San Luis de las Amarillas, was founded on the San Saba River in 1757 and named for the viceroy.
Amarillas also directed Spanish settlement of the lower Trinity River basin. In response to French penetration of this region, he called for the establishment of a garrison of thirty soldiers and a supporting mission manned by two friars from the Franciscan missionary college at Zacatecas. The viceroy also deemed it advisable to found a villa populated by fifty families, but that proviso was never realized. Near what is now Anahuac in Chambers County, another presidio named for the Marqués, San Agustín de Ahumada, took shape in 1756. The Marqués de las Amarillas likewise directed the founding of Santa Cruz de San Sabá Mission, which was established in 1757. One year later, Comanches and their northern allies attacked the mission and totally destroyed it. Under express orders of the viceroy, a punitive campaign of 1759, led by Col. Diego Ortiz Parrilla, sought vengeance against the offending American Indians. News of Parrilla's defeat on the Red River came near the end of Amarilla's tenure. He died at Cuernavaca in 1760; his interment was at the Santuario de la Piedad. He had profited so little from government service that he left his widow, the Marquesa de las Amarillas, without means of subsistence, forcing her to return to Spain where she was provided for by the generosity of Archbishop Rubio y Salinas. The military garrisons in Texas that had been named in honor of Amarillas were both abandoned in 1770.