The "Western Frontier" refers to the vast, largely uncharted territory in the western United States during the 19th century. This area was characterized by its rugged landscapes, including mountains, plains, and deserts, and was home to various Indigenous peoples. The expansion into this frontier was driven by the idea of Manifest Destiny, the belief that Americans were destined to expand across the continent. As settlers moved westward, they established new communities and engaged in activities like farming, mining, and ranching. The arrival of the Transcontinental Railroad in 1869 significantly improved transportation and communication, further encouraging migration. This period also saw conflicts with Indigenous tribes, leading to significant changes in their way of life.