Tribal lands are held in trust by the Federal by Indian Affairs...much like the title to your home (if you have a mortgage) by the bank that holds your mortgage. The Federal government does not hold title to tribal land, the tribe does (or, in some cases, the individual in the case of an individual allotment)
OK, Can you carry, openly or concealed on Tribal land...totally up to the tribal government, was before SB1743, still is. Tribal law only applies to members of the tribe, but when you are a guest on tribal land you need to know what kind of agreements the tribal government has made with state/county their reservation is located in.
Some tribes choose to recognize their state's license to carry, some do not. Some tribal LE has Law Enforcement rights equal to non-tribal LE when encountering a non-tribal member that is violating state law on tribal property, some do not. You really need to read the tribal law for that particular place. You can probably find those tribal laws on the net.
Our local tribe requires permission from the tribal council to carry on tribal land, except area's that are open to the general public (like a highway, gas station, etc). Now this is only true for the Colville Conferated tribes, on the Colville Reservation. Other tribes do it differently...like the Warm Springs tribe restricts tribal members, but follows State law for everyone else, even on tribal land...but then the Warm Springs tribe has a huge resort they run on their property too....