[[WMG: The islands are what's left of Atlantis.]]
[[spoiler: An ancient civilization]] destroyed by the sea a long time ago. It just makes sense. Ok, so it seems to be on the wrong ocean. But what kind of legend is 100% accurate?
* There's a mythic civilization of Mu supposedly located in the Pacific ocean. Depending on who you ask, it's either separate or synonymous with Atlantis.

[[WMG: Cox is to [[Discworld/NightWatch Carcer]] as [[Discworld/TheColourOfMagic Dr Rijnswand is to Rincewind]].]]
That is, they're alternate-universe analogues of each other.
* ...perhaps suggeting that ''Nation'' and that scene in ''Color of Magic'' actually take place in the same AlternateHistory version of Roundworld?
** Possibly it's the version from the original ''Science of Discworld'', that developed without the elves' assistance and left those differently-spelled signs behind at the space elevator's entry-bays. It's not impossible that the wizards' interactions with early humans in the second book gave the resulting iteration of civilization a different slate of place-names thousands of years later, while incidentally cultivating an unfortunate taste for things like sailfin-crocodile eggs and tree-climbing octopus.

[[WMG: Because Mau didn't get his "man's soul" yet, the 'new' island survived.]]
* Since he ''officially'' didn't have a soul, of course no-one would expect him to behave "normally", as in supporting '''all''' traditions. With so many different groups represented, things should have stayed fragmented for a longer period of time; Mau, however, could bring everyone together (also with enough willpower), and nobody would need to feel offended that he wasn't following any specific traditions; especially since they all ''knew'' him as the "boy with no soul".