In 1541, Francisco Vasquez de Coronado led an expedition of Spanish soldiers and others out of Pecos Pueblo in northeastern New Mexico and onto the southwestern Plains. After crossing the Pecos River valley, he ascended onto the High Plains of eastern New Mexico and northwestern Texas. On this landscape, he saw “no more land marks than if we had been swallowed up by the sea … there was not a stone, nor bit of rising ground, nor a tree, nor a shrub, nor anything to go by,” and he noted that “the country is so level that men became lost when they went off half a league. One horseman was lost, who never reappeared, and two horses, all saddled and bridled, which they never saw again. No track was left of where they went” (Hammond and Rey 1940).