In 1849, the California Gold Rush took hold in the Sierra Nevada. As tens of thousands of miners flooded the foothills, some became the first outsiders to make contact with the Sierra Nevada's indigenous peoples since Spanish explorers trooped through at the beginning of the 19th century.
Encounters between the miners and Native American tribespeople were often not amicable, and sometimes violent. Although trade relations were established, forced labor and even outright killing of Native Americans happened, too. The miners, settlers, ranchers, and other pioneers also brought with them diseases to which Native Americans had no natural immunity.
After California became a state in 1850, the federal government tried to persuade or force tribes in the Sierra Nevada to move to reservations in California's Central Valley. Unconvinced, most fought to stay where they were. An incident in which Miwok, Yokut, and other tribespeople attacked a miners' trading post lit the proverbial match.
In 1851 a state-sanctioned militia mostly made up of prospectors and miners calling themselves the Mariposa Battalion invaded Yosemite. Once they reached the Yosemite Valley, the group razed and set fire to the village of the Ahwahneechee, forcing the tribespeople onto reservations down in the Central Valley and capturing their leader, Chief Tenaya.
Not long afterward, Chief Tenaya left the reservation in the Central Valley and fled east across the Sierra Nevada to live with Paiute tribespeople in the Mono Lake area. But he didn't stay away from his homeland for long, returning to Yosemite Valley in 1853. He died later in a confrontation with Miwok tribesmen, allegedly over stolen horses.