Legal definition in the United States
The term tribe is defined in the United States for some federal government purposes to include only tribes that are federally recognized by the Bureau of Indian Affairs (BIA), established pursuant to the Alaska Native Claims Settlement Act [43 U.S.C. 1601 et seq.]. Such tribes, including Alaska Native village or regional or village corporations recognized as such, are known as "federally recognized tribes" and are eligible for special programs and services provided by the United States. The BIA, part of the US Department of the Interior, issues Certificate of Degree of Indian Blood, which tribes use as a basis for tribal enrollment.
Some tribes, such as the Little Shell Chippewa, do not have federal recognition, but are recognized at the state level using procedures defined by various states, without regard to federal recognition. Other tribes are unrecognized because they no longer exist as an organized group or because they have not completed the certification process established by the government entities in question.
Some federally recognized tribes are confederacies of more than one tribe. Historically, the State of California formed rancherias and Nevada formed Indian Colonies. Multi-ethnic entities were formed by the U.S. federal government or by treaty with the U.S. government for the purpose of being assigned to reservations. For example, 19 tribes that existed in 1872 combined at that time to form the Colville Confederated Tribes, which is now the single federally recognized tribe, Colville Indian Reservation in Washington state.