The Chehalis people or Tsihalis are a native people of western Washington state in the United States. They should not be confused with the similarly named Chehalis First Nation of the Sts'Ailes people along the Harrison River in the Fraser Valley area of British Columbia.https://en.wikipedia.org/wiki/Chehalis_people The Chehalis people of Washington consists of two divisions, speaking two distinct languages, which were not mutually intelligible: The Upper Chehalis or Kwaiailk and the Lower Chehalis, the boundary between the two groups was the confluence of the Chehalis River and Satsop River.