The Upper Cowlitz or Taitnapam, is a Northwest Sahaptin speaking people, part of the Confederated Tribes and Bands of the Yakama Nation.

The question concerns whether they had adopted the Sahaptin language from east of the Cascade Mountains, ceased to use their original, heritage language, and developed a separate Taitnapam / Upper Cowlitz / Lewis River dialect of Sahaptin, or whether they were Sahaptin-speaking people from east of the Cascade Range who came to occupy the Upper Cowlitz River Basin by conquest and intermarriage.

The season started in spring, when the Cowlitzes left their cedar houses along the river and streams by traveling via canoe and horseback to harvest camas bulbs, roots, barks, and grasses to make mats, fishnets, and basketry.

Generally, hunting and fishing were practiced all year round, but only roots and fruits had to be harvested seasonally.

The process is completed by placing a child onto a wooden board, usually covered with moss or loose fibers of cedar bark, then placing a pad between a piece of smooth bark, strapped on through the holes with leather bands, creating great pressure on the forehead.

When Chief Scanewea passed, Plamondon inherited most of his land and settled down with his wife on the Cowlitz Prairie where they bore four children: Sophie, Simon, Jr., Theresa, and Marianne.

[18] The first European who attempted to convert the Cowlitz to Christianity was Herbert Beaver, an Anglican, who settled with his wife at Fort Vancouver in 1836.

The couple set their sights on the Cowlitz tribe, only 50 miles southeast of Fort Vancouver, but growing tensions with John McLoughlin, the head at Fort Vancouver, prevented the couple from having any influence over the tribe; implementing their practices was with great difficulty.

[20] After conflicts arose with McLoughlin, Beaver and his wife headed home to London in 1838, to continue on their work.

[20] A once optimistic priest, he became discouraged when the Cowlitz tribe did not fully immerse themselves into Catholicism, and instead held onto sediments of Native spirituality.

[19] After the priest left, the Cowlitz reportedly told the French-Canadian farmers, "We want to do something for them, we will work, make fences, and whatever they wish us to do.

[citation needed] In 1924 the Cowlitz sent Frank Iyall as a delegate to congress for the American Indian Citizenship Act.

He also served as delegate for the recognition of the Cowlitz Indian Tribe which received approval from congress but a veto from President Calvin Coolidge.