Illarh was a planet located somewhere in the galaxy's Alpha or Beta Quadrants, situated near Federation territory. Illarh was the home of the Illarhi species. In the year 2373, Illarh was conquered without resistance by Dominion forces under the command of the Vorta Sejeel because of its proximity to Federation space. (STA - Tales of the Dominion War short story: "What Dreams May Come")