I haven't written this up yet.
This is the bare bones information.
Karianton is the nearest city to Atlantis which is not regarded by anyone as part of the Atlantean Empire. There are places closer to Atlantis which do not regard themselves as part of the Atlantean Empire, but Atlantis has a different view of the matter.
However, Karianton is not in any sense independent of Atlantis. Karianton's rulers are closely related to the Atlantean aristocracy. The current Prince of Karianton is a cousin of Duke Iazoq, and his wife is a sister of Emperor Atlantis Atlantor 22nd.
In principle, Karianton is an absolute monarchy. In practice, the Prince of Karianton decrees whatever his advisors, all local men, advise him to decree, except in cases where this concerns diplomatic relations with Atlantis. The local advisors accept that the Prince of Karianton knows more about this than they do.
While in Karianton, the player character(s) may hear rumours of large quantities of meteoritic iron lying unclaimed by anyone in a place called Vaatjan on the south coast.