Frosalia

Frosalia is the island North of Anta. Frosalia has mountains on the far North of it, which protects the rest of the island (and Anta) from high winds. If you were to travel here, you'd need proper winter-attire, and a fire pokemon or two. Without those, you would instantly freeze.
Many Ice-Pokemon are found here, either playing in the snow, or lurking deep in the caves in the mountains.