The universe containing the Shark Tooth Archipelago

Hard fantasy

These islands were formed as a result of an alien landfall. This created the material that formed the basis for the archipelago's technology.

The archipelago was formed by the planet fall of an alien entity. The fall was strong enough to shatter the crust into the concentric circles of the islands, but not enough to vaporize it. The tidal waves resulting it, however, rippled across the planet.

The arrival of humans to the archipelago is murky. The records of their presence and the growth of the nations go back many generations. The only general agreement is that a civil war broke out in the original civilization and much of the recorded history was destroyed. Both Arbas Gaelith and Sahaladir have their own histories on the nature of this feud, and both claim to have the true historical records of the archipelago's founding. Many researchers (Sam included) suspect that both histories were invented after the fact to give the respective nations a greater sense of legitimacy.

Earth-style physics. The alien presence introduces a pseudo-science factor to be explained.

All magic in the archipelago relates to the fallen entity. It is a multidimensional crystalline creature with pieces of it scattered across the archipelago. It's identity is the amalgamation of these pieces. The manipulation of any such piece is manipulation of the entire creature. Its multidimensional nature imparts unusual properties when joined with organic and inorganic material.

Consider this a soft magic system where the true scope of magic is not known and not particularly important. We are treating it more as a plot device than the drive behind major character mechanics.

Similar to early industrial western European and Scandinavian.

I suppose I was thinking most about A Wizard of Earthsea, wherein different islands represent their own sovereign identity. The concept was a more terrestrial rethinking of the multiple star systems that made up human civilization in the sci-fi version of the design.

The archipelago design is framed on the notion of an alien planetfall. The concentric islands represent the shattered earth that rose about the impact point. The impact was enough to shatter the crust, but not atomize it. It seems plausible to me that the events that created the archipelago are not unique and other similar island chains may exist. It also suggests a more complex larger universe than is currently being examined.