From the introduction: After the defeat of the Suel barbarians who invaded the northern Aerdi hinterlands from the Kingdom of the Fruztii in 109 CY, the Bone March was established by Overking Manshen as a fief to reward his victorious commanders. However, it soon became clear to the leaders of the Aerdi military that a further buffer was required if these new lands were to be protected from additional incursions from the north.