long ago because of some unknown reason there wizards of the world started to kill each other
A century ago, there was a demonic war that broke out in every country in the world, and it started because there was severe illness spreading through every nation. At that time, there were so many talented young talented magicians coming in to aspire to their careers. They wanted to use the knowledge that they had acquired over the years in the time of crisis and started treating the people who were sick. They get good results in the beginning and cure lots of people. The nations that know their end is near due to an unknown illness outbreak, as they will lose all the people of the kingdom due to disease, rejuvenate once more thanks to the mage's hard work all over the world.
All of the nations started to prosper once again, starting a new life after the pandemic.