Background of the world

World background:

Originally the floating islands didn't exist.
Due to the nature of the world, everyone had access to basic forms of magic (energy/essence manipulation). Magic was used primarily for entertainment and convenience, since that seemed to be the best use for it. Never-expiring candles, necklaces that kept you warm in the cold, drinks that changed taste based on the imbiber's preferences, so on and so forth. Eventually, however, a group of people decided to push the boundaries of magic and see just how much could be done with it.

Birth of Mages:

This group called themselves mages, and they learned to use magic in combat. They rapidly grew stronger than those who were not of their order, and as such eventually took control of the surrounding kingdoms so that they would have more resources that they could use to further their magical studies. The mages grew greatly in magical proficiency, and learned necromancy and other "dark" magics. Dark magic itself is not a thing, per se, but it refers to magic that is used in inhumane ways, such as controlling bodies or magically re-fusing bones to use skeletons as minions.

Fall of Mages:

At first the mages were watchful for rebellions among their subjects, but eventually they grew complacent, as they were not true rulers and were more interested in studying the magical arts than ruling. The mages learned that their powers were stronger the closer to the earth they were as if they were drawn to some ancient force, so they began to build cities downward into the depths of the earth, rather than up towards the sky.
During this time, a group secretly formed, bent on escaping from the mages. To make a long story short, they used their knowledge of magic to tear the four neighboring kingdoms from the earth along with a great tree that sat in the middle of all of the kingdoms. The tree's roots connected the four land masses to each other, keeping the now floating kingdoms from being separated. Now free from the mages, the kingdoms used what magic they knew to surround their floating lands with many clouds, so as to blend in to the sky and help protect them from being found. Since the Mages had the most advanced cities, the kingdoms would have to start over from scratch and rebuild themselves with the people they had. Each kingdom elected four exceptionally talented people from the group in their local kingdom that spearheaded this plan to oversee their affairs and to lay down how they should function going forward.
These people would later be known as the "Ancients" of each kingdom: The Ancient of War, the Ancient of Life, the Ancient of Sanctuary, and the Ancient of Lore.