The Allied Indian Tribes of British Columbia formed in June 1916 at a conference held in Vancouver, which consisted of the Nisga'a Tribe, Interior Tribes, and the Indian Rights Association. Prior to this conference, in February 1915, a meeting was held at Spences Bridge at which point the Interior Tribes of British Columbia became allied with the Nisga'a Tribe in support of the Nisga'a Land's Committee's 1913 Petition to His Majesty's Privy Council. At the 1916 Vancouver conference, the Indian Rights Association also committed to co-operation with the Nisga'a and Interior Tribes and there was consensus to reject the Federal Government's terms presented in a 1914 Order-in-Council (P.C. 0751-1914).
A provisional committee was formed in 1916 in Vancouver, and the first general meeting of the Allied Tribes was held at Vancouver and Spences Bridige in June 1919, at which point a permanent executive committee was formed. Arthur O'Meara served as general counsel for the Allied Tribes, and had previously acted as counsel for the Nisga'a (including during the 1913 Petition).