The Yakama Nation referred to Rattlesnake Mountain as Lalíik, meaning land above the water. Some historians speculate that the origin of the name Lalíik refers to the inundation of the Columbia River Plateau during the Missoula Floods, as Rattlesnake would have been one of the few mountains not completely inundated by flood waters reaching depths of 1200 ft (366 m). Geologists have found glacial erratics on Rattlesnake at heights up to this level. However, there is scant evidence placing human settlements in the area at the time of the floods, 12 to 13 thousand years ago. Lalíik is held sacred by native peoples of the Columbia Plateau, including the Nez Perce, Umatilla, Wanapum, Cayuse, Walla Walla, and Yakama, and remains a spiritual epicenter to this day.