Oz - Vixen's Wakanda

Like in the original novel, the Land of Oz is an actual place on Earth that you can visit, though it would be very tricky considering it's a lost continent hidden by magick located somewhere in the South Pacific Ocean. On top of that they're staunch isolationists.

https://en.wikipedia.org/wiki/Land_of_Oz

Oz is Vixen's equivalent of Wakanda from Marvel as it also has a rare indestructible metal that it refuses to share with the rest of the world aside from a select few - Ozerium!