Lyon

This appeal involves a dispute between an Indian tribe and the trustee of a bankruptcy estate over the rights of access to and occupation of a parcel of land completely surrounded by Indian reservation land. The district court had jurisdiction pursuant to 28 U.S.C. §§ 1331 and 1334. We have jurisdiction to hear this appeal pursuant to 28 U.S.C. § 1291 , and we affirm in part and vacate in part.

I.

The center of the parties’ dispute is “Section 16,” a parcel of about 657 acres in Pinal County, Arizona. The land surrounding Section 16 is part of an Indian reservation (Reservation) belonging to the Gila River Indian Community (Community), a federally recognized Indian tribe. We start with the history of Section 16 and the Reservation.

The Community historically occupied the land that is now south-central Arizona. See Gila River Pima-Maricopa Indian Cmty. v. United Staten, 24 Ind. Cl. Comm’n 301, 303, 335 (1970). Through the 1853 Gadsden Purchase, the United States acquired title to land from Mexico, including what is now Section 16. The following year, Congress adopted a law providing that when a survey was completed of the lands within the purchased territory, “sections…