The Agyn Peninsula is located in the western part of Thallan and is surrounded by the Irisus Sea to the north, the Savage Sea to the south-west, and Tirya Bay to the south-east. Nearby, there is the Yon-Chall Forest and the Vantyr Range. The Western part of the peninsula is uninhabited, with dark forests, thick bogs, perilous mountains and desolate barrens, roamed by wild animals, brigands and other dangers, while pirates terrorize its coastline.
There is one major city — Karthal, once a colony of Holy Falcon Empire and three smaller towns. Karthal is now a Free City but under the control of the Crimson Wizards of House Chimera after their fall from grace in the Seven Cities, after the Orc and Beastmen Rebellion.
Seahaven is another major city on the peninsula. It is here where the Windsword mercenary group is located. However, like Karthal, it is now under the rule of the Crimson Wizards.
The Agyn Peninsula was once part of the Shantiri Empire, the Elemental Forge still remains as proof. It harbors many Shantiri ruins, attracting all kinds of treasure-hunters and lore-keepers who hope to unlock their secrets. The Peninsula was once considered a part of the Holy Falcon Empire, although the Elves of Irollan and the Wizards of the Seven Cities have had its own claims on that lands.
The Blades of Erebos attempted to sow chaos throughout the peninsula by tricking the Empire, elves, and wizards into warring with each other. The plan involved Ajit and the Blackfang thieves guild planting evidence implicating one of the factions after Vayaron's forces attacked another. However, their plans for Karthal were ruined after Erebos and Salvin were killed in battle.
By the Sixth Eclipse and the Holy Griffin Empire, the peninsula has been under the rule of the Crimson wizards. Since their arrival the Peninsula is sometimes nicknamed "The Crimson Empire", although often derisively.