The part of the Sierra Nevada where the park is located was long considered to be a physical barrier to European American settlers, traders, trappers, and travelers. That situation changed in 1848 after gold was discovered in the foothills west of the range. Travel and trade activity dramatically increased in the area during the ensuing California Gold Rush. Resources depended upon by local Native Americans were depleted or destroyed, and disease brought by the newcomers spread rapidly through indigenous populations. Extermination of native culture became a policy of the United States Government.