One of the risks to employers and immigration is the use of Tribal Docs in B & C. The document lacks guidance on what is acceptable. More detail should be given if all Native America ID's ( even those not federally recognized such as Piscataway Convoy Tribe) on whether or not the document is acceptable. Also, some tribes have sold their membership ID's to aliens to get them work (Little Shell Pembina). The use of these documents does not help to combat an illegal workforce as they are not held to the Real ID Act.
There are indian Tribes throughout the world, but the lack of guidance makes it so that ALL Native Americans (regardless of orign) are authorized to work in the US.