The restricted allotment of any Indian may be leased for farming and grazing purposes by the allottee or his heirs, subject only to the approval of the superintendent or other officer in charge of the reservation where the land is located, under such rules and regulations as the Secretary of the Interior may prescribe: Provided, That this provision shall not apply to the Five Civilized Tribes.
[Mar. 3, 1921, ch. 119], [41 Stat. 1232].)