In the past, the Grasslands extended roughly from western Dunan to the ocean far to the west. However, at some unspecified point in the mid-300's, the Holy Kingdom of Harmonia launched an invasion of the region, gained large amounts of territory with ease thanks to a superior, organised military and plunging much of the region under Harmonian rule.
However, in 407, a man known only as the Flame Champion appeared in the region. Leading a group known as the Fire Bringer, the group attacked Harmonian convoys in the region beginning a period of guerilla warfare against their Harmonian occupiers. The war escalated over the following decade, with many clans joining the fight, the first to do so being the Duck Clan, until 417 when the Flame Champion offered himself up to Harmonia in exchange for the release of 5,000 Grassland prisoners. While this secured the prisoners freedom it also led to a drop in momentum for the Fire Bringer, allowing Harmonia to begin a brutal counter-attack, reconquering lost territories and plunging the people of the Grassland under further persecution.
A year prior to the completion of Brass Castle, 421, saw the rescue of the Flame Champion from Harmonian territory by the Fire Bringer. This daring rescue provided a great boost to the Grassland forces which had allied in the face of Harmonian invasion and the war flared up once again to the point of full-scale traditional warfare. The two armies clashed with each other numerous times over the next four years, with the technically superior Harmonian military struggling to overcome the zealous Grassland troops.
This led to a full-scale Harmonian invasion of the region in 425 with the moving of the Harmonian Army across the border. The sheer numerical superiority of the Harmonian Army now threatened to overwhelm the relatively small Grassland allied troops. However, the final battle of this, the original Fire Bringer War, saw the Flame Champion's True Fire Rune go out of control, decimating both armies with an enormous explosion. Unsure of the nature of this explosion and whether it was intended or not, Harmonia agreed to a secret non-aggression pact that would be valid for the next fifty years. Grassland territories under occupation at the time of the treaty were not released under these terms thus relegating such locations as the Kanaa Clan (modern-day Le Buque) to the position of Harmonian vassal states with its citizens only granted third-class status in Harmonian society. With peace with Harmonia secured for the foreseeable future, the tribes of the Grasslands focused on their own individual problems.