Khayar Seldnii Darn (concept)
The Khayar Seldnii Darn, or 'Two Swords War' in the Öltenic languages, was a legendary conflict between the Öltenic warlord Otached and the Kathuni general Xaoi Yaung Zayang, First Master of the First Banner to the Emperor and the last of the major Öltenic-Kathuni Wars. The war itself is named for the swords each general wielded for the conflict, Otached holding the legendary Iorne Seld and Yaung Zayang the equally legendary Eyon Faeng. It began when Otachad gathered a large force and smashed through the Kathuni border forts despite being outnumbered nearly three to one before sacking the city of Haoj'an, capital of the western state of Cheyyungjei.
Yaung Zayang, whose motives are different in most modern tellings of the story (most frequently stories say that either his brother was slain defending the border forts or his family was slaughtered in Haoj'an), requested permission from then-Emperor Xu Giang-Xu Yaon to take his personal banner west to slay the Öltenic warlord and find a way to permanently end the increasing Öltenic threat. Most likely remembering the Gayhan Campaign which had brought the Öltenis within viewing distance of the capital only thirty years prior during his father's reign, (the Öltenis being allowed to view the capital at all, even from afar, being seen as a devastating insult to the Emperor's lineage) he approved and sent a force of his personal Magi to accompany him.
While Otached faced a terrible defeat in the Battle of Kayang, he managed to escape across the Kathuni border where he used the spreading legend of his blade and his personal connections to other clans to gather the greatest host ever brought against the Kathuni, uniting almost all major Öltenic clans into a great host which soon fought and routed Yaung Zayang. Yaung Zayang, now under threat of death if he were to fail again, returned with three full Banners as well as the militia of four different states. The war ended with the Battle of Kayarang.