Illianin is the major port on the east coast of Myaasia. The Great Road that once led all the way to Carse today ends in Illianin. Most of the trade with the Thousand Islands passes through its docks. The population is made up in nearly equal parts of farmers (both originally from the area of Illianin and refugees from Carse) and Sagath, who settled down behind the walls of the city for protection against roaming unlife. Though there are tensions between the former enemies, violence rarely exceeds tavern brawl level. Many of the inhabitants have fought side by side in the Battle of Jon River, and the continued threat, both from the unlife and the evil cultists in the eastern swamps, serves to unite the townspeople.

In the third era, Illianin was little more than a small town, a waypoint along the Great Road between Carse and the Golden City of Baldemar. During the Unlife Wars, the town was a haven for the many refugees. After the armies of the lich Xanathar had been defeated and scattered by Chondra mere days before reaching Illianin, many of the previously hostile Sagath – mostly smaller tribes - sought the protection of the newly erected walls around the city, and after Carse had fallen to the plague, farmers from the surrounding lands also came to settle in Illianin. Also, with the fall of Carse, the only major port on the East Coast of Myaasia was gone and Illianin, conveniently located close to the delta of the Jon River, took up the slack. The city grew mainly towards the south in the direction of the Unreachable Sea to the point that the original location was all but abandoned.