Before European contact — and still today, American Indians of the Paiute, Shoshone, and Washoe tribes inhabited the land that is now Nevada. The first Europeans to explore the region were Spanish. They called the region Nevada (snowy) because of the snow which covered the mountains in winter like to Sierra Nevada in Spain. The area formed part of the Viceroyalty of New Spain, and became part of Mexico when it gained independence in 1821. The United States annexed the area in 1848 after its victory in the Mexican-American War, and it was incorporated as part of Utah Territory in 1850. The discovery of silver at the Comstock Lode in 1859 led to a population boom that became an impetus to the creation of Nevada Territory out of western Utah Territory in 1861. Nevada became the 36th state on October 31, 1864, as the second of two states added to the Union during the Civil War (the first being West Virginia).