The Great War is a war between different races that began so far in the past that nobody remembers clearly and ended at around six thousand years ago. The war was caused by the gods, or the Old Deus as they are later called, to obtain the Star Cup, which has the power to do anything and thus will be the crowned the Only God or the True God. The war was won by Tet by default in the end, and after Tet claimed the Star Cup, he forbid all violence and thus created the Ten Pledges.
During the war, the sky was bleached red and falling blue ash-like particles covered the land. These were said to be the remains of dead spirits, and were highly poisonous to any part of any living body it came contact with. The world seemed to have been much colder, although still warm enough for humans to not die. The attacks of the stronger races frequently transformed the land and changed the landscape. Much less animals lived during this time. Humans could only survive by living secretly in caves and sending scouts to scavenge the wreckages left from battles between other races.