Llano Estacado is a region in the southwestern United States that encompasses parts of northeastern New Mexico and northwestern Texas. It is a large mesa, or tableland, and relatively flat over most of its terrain. It is bounded on the north by the Canadian River, on the east by the Caprock Escarpment and on the west by the Mescalero Escarpment.
Llano Estacado is Spanish for staked plains. It is the southern end of the Great Plains and is part of what was once called the Great American Desert. The term staked plain arose after Spanish conquistador Francisco Coronado and his troops encountered this "sea of grass". Most authorities believe that the term originates from the stockade-like appearance of the geologic formations which form its boundaries. A minority believe that Coronado and his men drove wooden stakes into the ground so that they could find their way out of the tall prairie grass. However, later explorers found markers of rocks, buffalo bones, and dung, not wooden stakes.  An anecdotal version of the origin of the name claims that the "stakes" were the long, straight stalks of the yucca plants found in the region.
It should be noted that the horses of the conquistadors were the first to return to the Great Plains since their extinction in North America eons earlier, and that some horses would escape, thus giving horses to some of the Native American tribes in the succeeding centuries. Before this, the dog was their largest domesticated animal.
"El Llano Estacado" is a traditional folk song adapted by Tom Russell, which, according to Brian Burns (who has recorded a version of the song with Russell), is a tale in which the "subject falls victim to the whim of a sadistic señorita and decides to take on the West Texas desert to win her hand in marriage."