From publisher blurb:
Rethem is a feudal kingdom in western Hârn. Founded less than 100 years ago, the Kingdom of Rethem is the latest stage in a bloody evolution that started with Corani imperial conquest and passed through Morgathian revolt, barbarian conquest, Agrikan ascendancy, and a brutal attempt at feudalism by force. The political situation is still far from settled and the threat of civil war looms over the kingdom. With its history of violence, a rulership built on cunning and strength, and its shaky political structure, Rethem is viewed warily by its neighbors.
Rethem is an exciting kingdom for your Hârn campaign. Characters can become involved in the border skirmishes with the neighboring lands of Kanday and the Thardic Republic, explore the Peran wilderness to the north (home to the fierce Kuboran tribes), or become embroiled in the machinations of the various political and religious factions fighting for dominance of the region.
The Rethem Kingdom Module is the perfect companion to many other Columbia Games publications, including the city of Golotha, Bedenes and Hyen keeps, and the castles of Shostim, Tormau, and Ithiko.