Two things to hold onto
Boundaries, not inventories. Fredrik Barth argued that a group is not a fixed list of customs but a maintained boundary plus the signs people use to mark it. Art is a superb boundary sign: portable, visible at a distance, and readable by insiders in ways outsiders miss.
“Made for outsiders” does not mean fake. Haida argillite was carved for sale from the beginning; Inuit stonecut printing is a borrowed technique. Authenticity is largely a market category, not an anthropological one. Boas argued in 1927 that the arts of all peoples rest on the same human capacities and the same hard-won technical mastery — there is no ladder to climb.