The world has been at war for a long time. Tensions between the Shiosian Empire and the Astian Federation had finally come to a head many years ago, and they had unleashed decades of pent up fury at one another. High-grade magic developed into weapons of mass destruction and death as the years drug on. People were bred for their lineages and their abilities. Not everyone can wield magical weapons or magical power, and those that can are greedily used by the dueling militaries. It became illegal to have magical ability and not be a part of either military. Casters who refused were burned at the stake or otherwise executed.
Eventually it became a war of attrition: eventually the other side would run out of food, water, or magical components. Magic was developed to get past these shortcomings, but many died in this research process.
After 500 years of war, the only neutral party in the war, the Council of Elder Magi had had enough. They combined their power in a singular ritual meant to give at least some of the world peace. Large chunks of existing continents ripped from the crust of the earth and were magically held miles in the sky. Military activity has been banned here, so that everyone may live in peace.