The Kingdom of Irendi was once the western isles province of the Thyatian Empire, and the base for the powerful western fleet. The role of the fleet was to protect the trade routes from the western bread-basket of Darokin to the imperial capital of Thyatis. As imperial power waned, and the focus of the empire was more and more eastwards rather than westwards, the role of Duke of the Western Isles became more and more independent, and the region gradually devolved from imperial control.
The kingdom is actually more of a loosely knit federation of various mercenary and pirate fleets based on the various islands, the leader of which titles himself or herself king or queen of Irendi. The crown is therefore something of a temporary possession, and depends on the ruler being able to provide his or her followers with sufficient plunder to keep them happy. The obvious target is the trade from Darokin to Thyatis the protection of which was once their primary purpose, and which is mainly now carried by the ships of the Minrothad Guilds. Relations between Irendi and Minrothad are basically open warfare most of the time, for that reason.
Other nations regard Irendi as basically pirates and the kingdom as the haunt of pirates.
The inhabitants of Irendi are mercenaries and adventurers from all nations, gathered there like flotsam. There are also various native humanoids, including a large lizardman population on some of the islands.