Preston, I have attended numurous wildlife meetings over the years. I have never heard anyone argue conclusive evidence that elk existed here in eastern wash. prior to the plants from Yellowstone in the early 1900's. They have found some evidence of the indians using elk parts in the early days but they have not proven that they came from eastern wash. I personally think they traded other indians from outside the area to obtain these elk "parts". A logical guess would be they traded with indians from either Idaho/western Montana or from some coastal tribes.. In attending many of these meetings, I have never heard any of the Yakamas talk of their ancestors hunting elk. I feel that if they ever did it would have been brought forward along time ago.. So in your description of where the elk roamed I can agree with you for the most part but when you say wash. it should be western wash.