Whenever all privately owned lands except mining claims within the following-described area have been purchased and acquired as authorized in sections
of this title, the boundary of the Papago Indian Reservation in Arizona shall be extended to include the west half of section
; west half of section
, township 17 south, range 8 east; all of township 18 south, range 2 west, all of fractional township 19 south, range 2 west; and all of fractional townships 18 and 19 south, range 3 west, except sections
in township 18 south, range 3 west, Gila and Salt River meridian. This extension shall not affect any valid rights initiated prior to July 28, 1937, nor the reservation of a strip of land sixty feet wide along the United States-Mexico boundary made by proclamation of the President dated May 27, 1907 (35 Stat. 2136
). The lands herein described when added to the Papago Indian Reservation as provided in sections
of this title shall become a part of said reservation in all respects and upon all the same terms as if said lands had been included in the Executive order issued by the President on February 1, 1917: Provided, That lands acquired under sections
of this title shall remain tribal lands and shall not be subject to allotment to individual Indians.