Complex sentence: Reyes says that they often intermarried with the Swhy-ayl-puh (Colville), who had a very similar language; the territory of the latter was largely in the Colville Valley and intersected Sinaixt territory at Kettle Falls.
Split into simpler sentences: Reyes says that they often intermarried with the "Swhy-ayl-puh" (Colville), who had a very similar language. The territory of the latter was largely in the Colville Valley and intersected Sinaixt territory at Kettle Falls.