25 U.S.C. § 398
Unallotted land on Indian reservations other than lands of the Five Civilized Tribes and the Osage Reservation subject to lease for mining purposes for a period of ten years under section 397 of this title may be leased at public auction by the Secretary of the Interior, with the consent of the council speaking for such Indians, for oil and gas mining purposes for a period of not to exceed ten years, and as much longer as oil or gas shall be found in paying quantities, and the terms of any existing oil and gas mining lease may in like manner be amended by extending the term thereof for as long as oil or gas shall be found in paying quantities: Provided, That the production of oil and gas and other minerals on such lands may be taxed by the State in which said lands are located in all respects the same as production on unrestricted lands, and the Secretary of the Interior is authorized and directed to cause to be paid the tax so assessed against the royalty interests on said lands: Provided, however, That such tax shall not become a lien or charge of any kind or character against the land or the property of the Indian owner.
25 U.S.C. § 398