The Treaty of Point Elliott of 1855, is the lands settlement treaty between the United States government and the nominal Native American tribes of the greater Puget Sound region. in the recently formed Washington Territory (March 1853), one of about thirteen treaties between the U.S. and Native Nations in what is now Washington.The treaty was signed on 22 January 1855, at Point Elliott, now Mukilteo (Muckl-te-oh ), Washington, and ratified 8 March and 11 April 1859.

Lands were being occupied by European-Americans since settlement of the Washington Territory began in earnest from about 1845. And they needed to get these people out of the way. By and large, Native leaders were willing to sell their land (although they had utterly different conceptions of land use and no cultural comprehension of European-American property rights concepts). They rejected proposals for their relocation from Puget Sound country. Signatories to the Treaty of Point Elliott included Chief Seattle (si'ab Si'ahl) and Territorial Governor Isaac Stevens. Representatives from the Duwamish, Suquamish, Snoqualmie, Snohomish, Lummi, Skagit, Swinomish, (in order of signing) and other tribes also signed. The treaty established the Suquamish, Port Madison, Tulalip, Swin-a-mish (Swinomish), and Lummi reservations.

The Native American signers included: Suquamish and Dwamish (Duwamish) Chief Seattle, Snoqualmoo (Snoqualmie) and Sno-ho-mish Chief Patkanim as Pat-ka-nam, Lummi Chief Chow-its-hoot, and Skagit Chief Goliah. The treaty guaranteed both fishing rights and reservations. Reservations were not designated for the Duwamish, Skagit, Snohomish, and Snoqualmie peoples.
https://en.wikipedia.org/wiki/Treaty_of_Point_Elliott