The Ahlissa (Adri/Innspa) region is part of the Kingdom of Ahlissa, it consists of the Principality of Innspa and the Adri Marchland.
For the Living Greyhawk campaign, this region was attributed to Germany and Austria.
In the south of the former Great Kingdom, a nomination now claimed by Overking Xavener's United Kingdom of Ahlissa, lies the Principality of Innspa—formerly, prior to the devastating Greyhawk Wars, part of the Prelacy of Almor and for long an independent part of the Flanaess. Only recently has Princess Karasin of House Garasteth elected to give in to Xavener's advances and become a part of Ahlissa... not totally of her free will, some say.
West of Innspa lies the Marchland of Adri Forest, which has become the name for the portion of the Adri Forest east of the Harp River. While all parts of the Forest west of that river are claimed by Innspa, the Marchland has been given by the Overking to his cousin, Prince Molil, who is determined to bring all of the Adri under Ahlissa's banner. This is the setting into which your character is thrust, should she choose to adventure in the Adri Forest or its surroundings—say, the southern Flinty Hills. This is disputed land, and opportunities for adventures abound. Most of the people living in the Adri Forest reject the rule of the Great Kingdom, even nominally, as staunchly as they once resisted advances by the Kingdom of Nyrond.(snip)
From "Area Introduction - Ahlissa" (issued by the German LG triad in 2000)