The Yahi were a California tribe, near what is now Sacramento in the Mill Creek area. They were one of the four Yana tribes, and spoke a language from the Hokan family. When the Gold Rush hit California in 1849, the combination of land loss, mutual aggression, and disease virtually wiped all of the Yana tribes out, and by about 1860 only a group of forty or so Yahi remained.

Those forty stayed in hiding until 1908, when two surveyors for Oro Light and Power came across an Indian man fishing in a creek. Merle Apperson, the surveying team's guide, was convinced by the two to look for whatever camp the Indian had come from. He and a few others found it the next day. As they got to the camp, two of the four remaining Yahi heard them coming and escaped into the woods, ignoring calls made by the explorers. They left a woman who would later prove to be Ishi's mother behind, hidden under blankets. The exploring group decided to loot the camp, with only Apperson (by his account) giving any protest. They took all of the stored food and utensils needed for the Yahi way of survival, and reported back to the surveyors that the Indians wouldn't be a problem.

Ishi was the man who'd been seen fishing, and was still on his foraging expedition during the looting. He arrived back to find his only male companions gone, and his mother alone without anything to eat. Still, the two tried to continue to live as Yahi, and Ishi continued himself after his mother died a short time later. Without any support or companionship, though, the last Yahi was doomed to impossible living conditions. By 1911, he was starved enough to leave the woods behind and try to get help from the white settlers.

He turned himself in near the town of Oroville, nearly dead. Held in a cell by the sheriff and mentioned in newspapers as a "wild man," he attracted the attention of two University of California anthropology professors, Alfred L. Kroeber and T. T. Waterman. They had already been looking for the man seen fishing by the surveyors, and were also generally interested in finding unacculturated Indians. Ishi went with them to the university's anthropology museum, where he would stay for the rest of his life.

Ishi generously collaborated with the anthropologists as well as he could, although both he and they had to learn pieces of the other's language to communicate. He taught the anthropologists about Yahi living areas and hunting, letting all the place and technique names be recorded to wax cylinder. He also made hundreds of arrowheads and knapped blades, sometimes demonstrating the process for museum visitors. Interestingly, members of Yana tribes have a taboo against saying their name or the names of the dead, so his real name was never known. Kroeber gave "Ishi" as the Indian's name whenever it was needed, although Ishi is simply the Yahi word for man.

In late 1914, Ishi came down with tuberculosis, which he tried to get rid of by staying with Waterman's family in Berkeley over the summer. Unfortunately, like all aboriginal Americans, Ishi had no resistance to it, and died on March 16, 1916. He was cremated, and his remains are buried in a Colma, California, cemetery.

There has been recent revival of interest in Ishi for two reasons. First, a group of research archaeologists at the University of California, Berkeley has discovered that the arrowheads Ishi made weren't made in the traditional Yahi style. Instead, they are closer in design to Californian Wintu artifacts. The archaeologists have suggested that this points to intermarriage between Yahi and Wintu peoples, and Ishi being taught the skill by a Wintu relative. Even though the Yana and Wintu were enemies, mutual taboos against incest may have forced them to intermarry near the end of both cultures' lives. Another reason for interest in Ishi is because his preserved brain (!) recently surfaced at the Smithsonian Institute in Washington, DC. Apparently, it had been shipped to the institute by Kroeber, who was at the time still young and possibly wanted to impress a senior scientist. As mandated by the Native American Grave Protection and Repatriation Act, it was returned to California for burial in 1999.