 Combination forms are common, such as Cariboo-Chilcotin, and Thompson-Okanagan, and these often turn up in names of governmental administrative districts, electoral districts and private or public organizations.All often correspond to linguistic and cultural-political divisions of the First Nations as aboriginal history was also shaped by the landscape's isolating and defining characteristics as settler culture.The main historical subregions, with their own subregions an irrespective of very common overlaps between some areas, and in their most common forms, are as follows