The Land of Oz

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!