Although many settlers arrived via the trails from Santa Fe or La Veta Pass, several routes over the Sangre de Cristos into the valley were well-known to American Indians and increasingly used by settlers in the late 1800s.Medano Pass, also known as Sand Hill Pass, and Mosca Pass, also called Robidoux’s Pass, offered more direct routes from the growing front range cities and dropped into the valley just east of the Great Sand Dunes.After lakes within the valley receded, exposed sand was blown by the predominant southwest winds toward the Sangre de Cristos, eventually forming the dunefield over an estimated tens of thousands of years.Evidence of human habitation in the San Luis Valley dates back about 11,000 years.The explorers were soon followed by settlers who ranched, farmed and mined in the valley starting in the late 19th century.The park was first established as a national monument in 1932 to protect it from gold mining and the potential of a concrete manufacturing business.Modern American Indian tribes were familiar with the area when Spaniards first arrived in the 17th century.The traditional Ute phrase for the Great Sand Dunes is Saa waap maa nache, "sand that moves." Jicarilla Apaches settled in northern New Mexico and called the dunes Sei-anyedi, "it goes up and down." Blanca Peak, just southeast of the dunes, is one of the four sacred mountains of the Navajo, who call it Sisnaajini.
Sediments from the surrounding mountains filled the valley over geologic time periods.The first historic peoples to inhabit the area were the Southern Ute Tribe, while Apaches and Navajo also have cultural connections in the dunes area.In the late 17th century, Don Diego de Vargas—a Spanish governor of Santa Fe de Nuevo México—became the first European on record to enter the San Luis Valley. Frémont, and John Gunnison all travelled through and explored parts of the region in the 18th and 19th centuries.Still pushing southwest, and confused about the location of the Arkansas River, Pike crossed the Sangre de Cristos just above the Great Sand Dunes. at the foot of the White Mountains [today’s Sangre de Cristos] which we were then descending, sandy hills…When we encamped, I ascended one of the largest hills of sand, and with my glass could discover a large river [the Rio Grande] …The sand-hills extended up and down the foot of the White Mountains about 15 miles, and appeared to be about 5 miles in width.Their appearance was exactly that of the sea in a storm, except as to color, not the least sign of vegetation existing thereon. Frémont was hired to find a railroad route from St. He crossed the Sangre de Cristos into the San Luis Valley in winter, courting disaster but proving that a winter crossing of this range was possible.