18 U.S.C. § 1151 : US Code - Section 1151: Indian country defined

      Except as otherwise provided in sections 1154 and 1156 of this
    title, the term "Indian country", as used in this chapter, means
    (a) all land within the limits of any Indian reservation under the
    jurisdiction of the United States Government, notwithstanding the
    issuance of any patent, and, including rights-of-way running
    through the reservation, (b) all dependent Indian communities
    within the borders of the United States whether within the original
    or subsequently acquired territory thereof, and whether within or
    without the limits of a state, and (c) all Indian allotments, the
    Indian titles to which have not been extinguished, including rights-
    of-way running through the same.