The report, shared first with the Associated Press, identifies 10 tribal nations that have “aboriginal title, congressional title and treaty title to lands within Colorado” and details the ways the land was legally and illegally taken. It determined that many of the transactions were in direct violation of treaty rights or in some cases lacked title for a legal transfer.

“Once we were removed, they just simply started divvying up the land, creating parcels and selling it to non-Natives and other interests and businesses,” said Dallin Mayberry, an artist, legal scholar and enrolled member of the Northern Arapaho Tribe who took part in the Truth, Restoration and Education Commission, which compiled the report.