Spires

The Spires are thirteen large mountain islands that surround the mainland, with several having an unnatural, tall spiral-like shape that pierces up toward the sky, hence their name. Remnants of the spire crystals are said to be found here, but the environment and monsters found on each are extremely hostile and challenging due to the effects divine magic has had over the millenia, mutating and changing the creatures as well as the environment itself. 
In the year 1433AC, the Three Powers fought a war to control Agartha's mainland, which would by extension give the victor the ability to set out on succesful expeditions into the outer islands. Some early expeditions were conducted but were met with outright failure, as the nations lacked the ability to defend their colonies while also committing capable magi to missions to the spires.