From the U.S. Department of the Interior
Some people want to become enrolled members of a federally recognized tribe. Others want to verify a family tradition (belief, fact or fiction, passed from generation to generation) that they descended from an American Indian, either in their distant or near past. While others might want just to learn more about the people they descend from and where they lived.
When establishing descent from an American Indian tribe for membership and enrollment purposes, the individual must provide genealogical documentation. The documentation must prove that the individual lineally descends from an ancestor who was a member of the federally recognized tribe from which the individual claims descent.
When people believe they may be of American Indian ancestry, they immediately write or telephone the nearest Bureau of Indian Affairs (BIA) office for information. That is not the best place to start. Many people think that the BIA retrieves genealogical information from a massive national Indian registry or comprehensive computer database. This is not true. Most BIA offices, particularly the central (headquarters, Washington, DC) and area (field) offices do not keep individual Indian records and the BIA does not maintain a national registry. The BIA does not conduct genealogical research for the public.