It's quite simple.
IF you are a Native American, and IF you are in eastern Oklahoma, and IF you commit a crime, you are then subject to the res jurisdiction, and federal jurisdiction, but NOT state jurisdiction.
It transfers exactly ZERO land to anyone, and applies to VERY FEW people.
As an aside, it appears that Oklahoma not only knew this, but wanted to put this rapist of a 4 year old up to SCOTUS so that SCOTUS would be too reviled to grant his petition.
Oklahoma has a bad history of dealing poorly with the indian reservations. They thought this case would grant them sovereignty over them. They figured wrong.