I never quite understand the legal status of Indian reservations. The Indians are American citizens but the Indian reservations are considered independent countries for certain purposes.
Perhaps in this case these Indians are saying that they don’t recognize the us-mexico Border because the Border runs through their reservation??
My understanding is Indian reservations are on federal lands within the states. They are under the authority of the feds and subject to the Constitution as federal “territories”. They certainly do not trump the constitutional requirements that the feds prevent invasion which is the purpose of the wall.
Treaty Indians are enshrined in the US Constitution, only they are granted Rights by virtue of treaty - the Amendments are privileges granted to all others and, unlike Treaty Indian Rights, can be revoked at any given time - at least according to SCOTUS.
The Constitution, according to SCOTUS, grants Treaty Tribes Sovereign status, giving them Rights which are not applicable to non-Indians, ie you, me.
The Reservation Indians are saying they need more money for the ruling families so they can maintain the life styes they would like to become accustomed to. Non-ruling families are just tokens for generating more income for the few. All of that and more is why most Indians do not live on Reservations.