There have been plenty of challenges where the objective is wanking a particular ethnicity. But these are generally ethnic groups most people have at least heard of, such as the Ainu, Samaritans or Zulu.
So, with this in mind, your challenge is to wank a more obscure ethnic group.
Depends on your definition of obscure. The TL in my signature, while in general being a PNW/California Indian wank by virtue of its agricultural PoD, gives certain groups (well, their ATL equivalents) an even bigger boost. For instance, I don't know if can be called Nuu-chah-nulth/Nootka especially obscure as far as American Indian peoples go (in that area there's more obscure groups by virtue of smaller numbers and/or their earlier destruction), but having an alternate version of them expand quite a ways down the Pacific Coast should count for something. I justified it by their OTL expertise at whaling (rather ancient) and an actual expansion to the mainland they did (the origins of the OTL Makah people) plus their frequent slave raiding (although that was common amongst most PNW cultures).
The most important reason would be a TL-specific push/pull factor where they want more land (especially coastal land, since their land is overcrowded), wealth, and slaves, and the best way to get that is by raiding other people and eventually subjugating them and inviting in followers, allies, and relatives to their new area. Over enough time and through cultural pressure the local populations assimilate to their culture/language, leaving a big chain of offshoot cultures stretching down the West Coast.
Other than that I've occasionally written some for other obscure cultures. I'd consider the Punic people of Late Antiquity obscure (unlike their more famous Carthaginian ancestors), but I think it's plausible to have them settle Malta (and neighboring islands i.e. Lampedusa) and then avoid Malta's Arabization and then persist until modern times.
A Berber wank, with many different potential PoDs from circa Carthaginian times to the middle medieval period, could be fascinating.
Easiest way could be to keep Morocco Berber, and that's possible even with a post-Islamic conquest PoD.