Map showing historical tribal territories in Washington State.
Own work based on: Washington areas map-fr.svg, Duwamish.png, Chehalis.png, Cowlitz.png  and Chinook.png

Other tribes : {http://www.lib.utexas.edu/maps/united_states/early_indian_west.jpg] (Public Domain) ; some borders of tribes confirmed with this ancient map [1]. All the borders of tribes are rough.
Bourrichon