Nuñez, Alvarez, Spanish sailor and explorer, surnamed Cabeça de Vaca, was born about 1490. He was second in command of the ill-fated expedition under Narvaez to Florida in 1527. At that time Florida included all the unexplored region of the Mississippi valley. When Narvaez was lost at sea Nuñez, with a few of the survivors, continued westward along the gulf coast until they were cast ashore on an island, presumably near the present boundary between Louisiana and Texas. They succeeded in reaching the mainland, and for six years were prisoners among the Indians. In the spring of 1536 Nuñez and three of his companions arrived in the Spanish settlements in the western part of Mexico. Soon after that he returned to Spain, and in 1540 was made governor of the Rio de la Plata. He explored the valley of the La Plata and conquered several Indian tribes, but upon charges preferred by his lieutenant, de Irala, he was summoned to Spain, tried, found guilty and banished to Africa. Eight years later he was recalled by the king and appointed judge of the court at Seville, where he died in 1564. Some twenty years before his death there was published at Valladolid an account of "the Shipwrecks of Alvarez Nuñez," written by his secretary, with notes and comments by himself. In this work mention is made of a river which "poured such a large stream into the Gulf that we took fresh water from the sea," and upon this statement some writers have tried to establish the claim that Nuñez discovered the Mississippi before De Soto.

In 1851 Buckingham Smith, while secretary of the American legation at Madrid. found and translated the narrative of Nuñez's wanderings in the interior of America, written at Culiacan in May, 1536. According to his own account he was something of a trader while among the Indians, as he tells how they employed him to go from one place to another for things of which they had need, the Indians being unable to do so themselves because of the hostility among the tribes. He says his chief wares were "pieces of sea snails and their cones, conches that are used for cutting, and a fruit like a bean of the highest value among them, which they use as a medicine and employ in their dances and festivities. There are sea beads also, and other articles. Such were what I carried into the interior; and in barter for them, I brought back skins, ochre with which they rub and color their faces; and flint for arrow points, cement and hard canes of which to make arrows, and tassels that are made of the hair of the deer and dyed red."

The occupation apparently suited him, as it left him at liberty to go where he pleased, and was finally the means of permitting him to make his escape from captivity. He was probably the first white man to traverse the western plains, and is believed by some to have followed the Arkansas river from the neighborhood of Great Bend to near Dodge City, whence he proceeded southwest toward New Mexico. It was the report of Nuñez and his companions that led to the Coronado expedition (q. v.) a little later in search of the seven cities of Cibola.