The Beast War (獣人戦争 Kemonohito Sensou?) was a conflict that occurred 100 years prior to the events of Tales of the Tempest. It was a civil war among the Leymon race of people spurred by the Leymon leader, Couber.
Couber once ruled over the Leymon people in a flourishing region yielding the City of Leymon and various other infrastructures. One day, a wandering human traveler, later revealed to be King Areulla VIII, approached him and intrigued him with the idea of Life Magic, an art capable of supposedly resurrecting the dead. Couber was told to sacrifice the lives of his people to fashion gems known as Pensients, which serve as catalysts for the Precepts of Life Magic, but was met with the hostility of the Leymon people, spurring the Beast War. Countless lives were lost as a result, a vast majority being petrified into stone as a result of Life Magic, which Couber believed would be worth it in the end if he could use this same power to resurrect them.
King Areulla's deception of Couber filled him with guilt, and he fled with a Pensient to extend his lifespan dramatically. He eventually settled in the remote village of Adelhabith. Following the conflict, the Leymon survivors were left with little choice but to forfeit rule of the continent to humans, at that time a small and weak race. The Life Magic rendered the City of Leymon a graveyard of petrified victims, and the entirety of the surrounding region was reduced to a desert-like wasteland of crumbling monuments. To the modern populace, the truth of the Beast War is veiled in mystery, with most unaware of it entirely.