Each tribe/reservation has it's own laws. The tribal laws can only be enforced on tribal members, the tribal police generally must contact the sheriff or state patrol to arrest a non-tribal member...however...they can boot you off the reservation if you do not follow their laws while a non-tribal guest.
Out here, most of the tribes have some sort of provision for legal carry or partial legal carry on reservation property per state license/law, but that is not something you should assume.
If you have a reservation that you like to hunt or fish on, it would be best to contact the Tribal chief LEO or the tribal council on how they are going to handle non-tribal members on OC or CC. Even if they have no restrictions, it will be good PR, as it will show they have a right to control their own property. (just as you have the right to control your own property) If you want, consider a reservation as tribal corporate private property and youw ill do just fine.
BTW: A lot of the larger reservations have their tribal laws online. Good place for contacts too.