25 U.S.C. § 391 : US Code - Section 391: Continuance of restrictions on alienation in patent

Search 25 U.S.C. § 391 : US Code - Section 391: Continuance of restrictions on alienation in patent

Prior to the expiration of the trust period of any Indian
allottee to whom a trust or other patent containing restrictions
upon alienation has been or shall be issued under any law or treaty
the President may, in his discretion, continue such restrictions on
alienation for such period as he may deem best: Provided, however,
That this shall not apply to lands in the former Indian Territory.