Webthe yakamas themselves originated from several groups that occupied the yakima valley from the headwaters of the yakima river, in the cascades, to the stream's junction with. Webakama indian reservation in south central w ashington state. Leaders who signed the treaty were: Weblet’s delve into the fascinating facts about yakima, uncovering its captivating history, diverse attractions, and the warm community spirit that defines this remarkable city. Webin 1870, settlers began referring to a small village with two stores as yakima city.