The battle between Ceiphied and Shabranigdu
Ages ago when the "staffs" were created, the battle between Flare Dragon Ceiphied and Ruby Eye Shabranigdu had already begun. Nobody knows how long the two powers fought, but it is known that some conclusion to the battle was reached approximately 5000 years ago. Ruby Eye's body was split into seven parts and sealed, while Flare Dragon, totally spent, sunk into the Sea of Chaos. However, Ruby Eye was only sealed -- not destroyed -- and Flare Dragon left behind four parts of himself -- the Earth Dragon Lord, Water Dragon Lord, Fire Dragon Lord, and Sky Dragon Lord -- to defend against Ruby Eye. In other words, the battle has not really ended.
Kouma-sensou (War of the Resurrection of the Demon King)
The war between the Water Dragon Lord and the Demon King of the North was brought about by Hellmaster Fiblizo approximately 1000 years ago. At the start of the war, Mazoku attacked the dragons of Dragons' Peak, and there was a sharp increase in number of attacks by demons, which shows that the Hellmaster had no intention of attacking the Water Dragon Lord immediately. The purpose of these actions was probably to awaken Ruby Eye who had been sealed within members of the human race.
This plan works, successfully resurrecting one of the seven parts of Ruby Eye, the Demon King of the North, who then wages war on the Water Dragon Lord. What the Mazoku did during this battle was create a "god-sealing field" by placing Hellmaster Fiblizo, Deep Sea Dolphin, Greater Beast Zelas-Metallium, and Dynast Grauscherra in the north, east, south, and west points of the Kataart Mountains, where the Water Dragon Lord resided. This weakened the Water Dragon Lord. By using Chaos Dragon (who was also a dragon) as a medium, the Demon King of the North managed to offset the difference between the one-fourth of Flare Dragon and the one-seventh of Ruby Eye.
In the end, the Water Dragon Lord was defeated, but the Demon King of the North became unable to move from the Kataart Mountains. This enormous battle involved humans, elves, dragons, and Mazoku. As a result of this battle, the power of the gods, which was one of the few ways to fight against Mazoku, was lost.