In 1865, Ishi and his family were attacked in the Three Knolls Massacre, in which 40 of their tribesmen were killed. Although 33 Yahi survived to escape, cattlemen killed about half of the survivors. The last survivors, including Ishi and his family, went into hiding for the next 44 years. Their tribe was believed to be extinct. Prior to the California Gold Rush of 1848–1855, the Yahi population numbered 404 in California, but the total Yana in the larger region numbered 2,997.