Taboos about beast control and great dangers

Introduction: Why did the tiger clan, which was not famous among the beasts, suddenly roar into the sky and look like it was about to become the overlord of the world? Why did the Zerg race, which has always been at the lowest level in the world and regarded as food by the bird race, cause such a catastrophe? He would rather destroy himself than kill all races crazily. Why did the wolf clan, known as the most united and powerful in the world, suddenly split apart and even fight each other with swords? The Dragon Clan, which has always been extremely arrogant and is known as the Supreme of Ten Thousand Demons and the Leader of All Spirits, is why is it that a strange dragon comes to the door frequently and beats them with no temper?