Originally, the region was part of the vast and sprawling Diocese of Rupert's Land, which at the time encompassed all of present-day Canada west of Ontario. Anglican activity in the Far North primarily took the form of missionary work among the Aboriginal First Nations and Inuit, undertaken for the most part by the evangelical Church Mission Society. In 1874, the Diocese of Rupert's Land was split into four dioceses one of which, Athabasca, included the present-day Diocese of The Arctic. In 1892, Atherbasca was subdivided to create the Diocese of Selkirk (coterminous with the Yukon) and the Diocese of Mackenzie River (coterminous with the Northwest Territories).