On July 24, 1847, a band of Mormon pioneers who had crossed the Great Plains and hauled their wagons over the Rocky Mountains descended into the Salt Lake valley. They settled alongside the Indians there in an immense, self-contained region covering more than 220,000 square miles aptly named the Great Basin because its lakes and rivers have no outlet to the sea. Within ten years of their arrival, the Mormons had established nineteen communities extending all the way to San Diego, California. But theirs was not a story of splendid isolation. The Mormon way of life was under a constant strain from interactions with miners, solders, explorers, mountain men, Indians, the Pony Express, railroad builders, federal officials, and an assortment of other "Gentiles." This is the definitive, dramatic, and multifaceted study of the Great Basin, unifying its history with its geography.