The Wanapum tribe of Native Americans formerly lived along the Columbia River from above Priest Rapids down to the mouth of the Snake River in what is now the US state of Washington. The name "Wanapum" is from the Sahaptin wánapam, meaning "river people", from wána, "river", and -pam, "people". Today they are enrolled in the federally recognized Confederated Tribes and Bands of the Yakama Nation. In prehistoric times, the tribe's territory was an excellent salmon-fishing area. It is unknown which tribes were overthrown by the Wanapum tribe when they claimed their ancestral land, or what happened to the original settlers that migrated from NE Asia centuries before the Wanapum and other tribes finally settled in the area. Because of the lost primitive and scarce archeology of the region, these secrets may never be known, and those people never acknowledged.

The tribe made houses from tule and cut over 300 petroglyphs into the basalt cliffs. In 1805, according to the journals of the Lewis and Clark Expedition, the Wanapum, led by their chief Cutssahnem, greeted the expedition and treated its members well, sharing food and entertainment. Captain Clark’s journals provide descriptions of their dwellings, clothing, and physical characteristics.

In the 1800s, a new Native religion, called Washane, Washani or "Dreamer Religion", was created by a spiritual leader of the Wanapum named Smohalla. Adherents to this religion believed that the white man would disappear, if rituals and traditional life was adhered to; instead of participating in armed conflicts, the people prayed. Whether due to this religion or for other reasons, the tribe never fought white settlers, did not sign a treaty with them, and as a result retained no federally recognized land rights.