By the first decade of the 20th century, Euro-Americans had so overwhelmed the North American continent that scarcely any Native Americans remained who had not been assimilated into Anglo society to some degree. Ishi appears to have been something of an exception. Found lost and starving near an Oroville, California, slaughterhouse, he was largely unfamiliar with white ways and spoke no English.
Authorities took the mysterious Indian into custody for his own protection. News of the so-called "Stone Age Indian" attracted the attention of a young Berkeley anthropologist named Thomas Waterman. Gathering what partial vocabularies existed of northern California Indian dialects, the speakers of which had mostly vanished, Waterman went to Oroville to meet the Indian. After unsuccessfully hazarding words from several dialects, Waterman tried a few words from the language of the Yana Indians. Some were intelligible to Ishi, and the two men were able to engage in a crude dialogue. The following month, Waterman took Ishi to live at the Berkeley University museum, where their ability to communicate gradually improved.
Waterman eventually learned that Ishi was a Yahi Indian, an isolated branch of the northern California Yana tribe. He was approximately 50 years old and was apparently the last of his people. Ishi said he had wandered the mountains of northern California for some time with a small remnant of the Yahi people. Gradually, accident or disease had killed his companions. A white man murdered his final male companion, and Ishi wandered alone until he reached Oroville.
For five years, Ishi lived at the Berkeley Museum. He and Waterman became close friends, and he spent his days describing his tribal customs and demonstrating his wilderness skills in archery, woodcraft, and other traditional techniques. He learned to understand and survive in the white world, and enjoyed wandering the Bay area communities and riding on the trolley cars. Eventually, though, Ishi contracted tuberculosis. He died on March 25, 1916, at an estimated age of 56. His body was cremated according to the customs of his people.