This is the process of defining nations in fantasy settings is to have each group be under the domain of one kind of magic. The main appeal to this is, naturally, the easy convenience of being able to define who is from what nation, since they'll have the appropriate elemental affinity to go with it, and the trappings of the culture itself will be clearly delineated by that element as well. This is often paired with tropes like Single Palette Town
in order to get the full effect. On the downside, this can sometimes result in a Planet of Hats
situation on a small scale, since all members of a specific nation must, by definition, fit into the general archetypes of their nation's element.
- Avatar: The Last Airbender features this prominently- elemental "bending" is limited to characters from the appropriately named nation that engages in use of that element. Moreover, the nations themselves are easily defined by those elements. The Air Nomads, when they were still around, largely lived in high-up temples which only they could glide to. The Water Tribe lives at the poles (where they are naturally surrounded by water), except for one offshoot that lives at a swamp (which is mostly surrounded by water).
- Skies of Arcadia uses this for all the defined nations. Though "magic" figures largely as a game mechanic, the cultures are all clearly influenced by the kinds of moonstones they have access to- Valua has a strong industrial sector powered by electricity, Ixataca has lots of trees, and Yafutoma has ships that can fly unusually high. Nasr mostly just has sand, but they manage.