2 Answers

Pay back I guess. They sure got jerked over (if you are referring to American Indians...)....

Tribal Government funds are used to provide staff at the Bureau of Indian Affairs (BIA) agency office, or hire staff under a tribal Indian self-determination contract to perform tribal government services at the tribal/agency level. Support provided includes research and preparation of Certificate of Degree of Indian Blood (CDIB) forms, review of tribal resolutions, liquor ordinances, proposed governing documents requiring action by the BIA line officials, preparation of membership rolls for special (Secretarial) elections or for per capita distributions, and administration of special elections per 25 C.F.R. 81. The staff also meets with tribal enrollment offices or committees on enrollment/disenrollment matters and appeals. In some cases, the Aid to Tribal Government (ATG) funds directly support the activities of the tribal contractor/tribal officials in carrying out contracted activities on behalf of the Bureau and the tribe.

Read more>>>>http://www.bia.gov/WhatWeDo/ServiceOverview/TribalGov/index.htm 

As for treaties in the U.S.A. see them here>>>http://digital.library.okstate.edu/kappler/vol2/toc.htm