The US Supreme Court has ruled about half of Oklahoma belongs to Native Americans, in a landmark case that also quashed a child rape conviction.
The justices decided 5-4 that an eastern chunk of the state, including its second-biggest city, Tulsa, should be recognised as part of a reservation.
Jimcy McGirt, who was convicted in 1997 of raping a girl, brought the case.
He cited the historical claim of the Muscogee (Creek) Nation to the land where the assault occurred.
What does the ruling mean?
Thursday's decision in McGirt v Oklahoma is seen as one of the most far-reaching cases for Native Americans before the highest US court in decades.
The ruling means some tribe members found guilty in state courts for offences committed on the land at issue can now challenge their convictions.Only federal prosecutors will have the power to criminally prosecute Native Americans accused of crimes in the area.
Tribe members who live within the boundaries may also be exempt from state taxes, according to Reuters news agency.
Some 1.8 million people - of whom about 15% are Native American - live on the land, which spans three million acres.
What did the justices say?
Justice Neil Gorsuch, a conservative appointed by US President Donald Trump, sided with the court's four liberals and also wrote the opinion.
He referred to the Trail of Tears, the forcible 19th Century relocation of Native Americans, including the Creek Nation, to Oklahoma.
The US government said at the time that the new land would belong to the tribes in perpetuity.
Justice Gorsuch wrote: "Today we are asked whether the land these treaties promised remains an Indian reservation for purposes of federal criminal law.
"Because Congress has not said otherwise, we hold the government to its word."