 They are part of the Interior Salish ethnological and linguistic grouping.The Okanagan are closely related to the Spokan, Sinixt, Nez Perce, Pend Oreille, Secwepemc and Nlaka'pamux peoples of the same Northwest Plateau region.At the height of Okanagan culture, about 3000 years ago, it is estimated that 12,000 people lived in this valley and surrounding areas.