Elemental Age
Powerful Elementals created the physical world that we know today. Fire, earth, water, air, each of them fought for supremacy, trying to shape the world to their liking. Nothing resembling life we know today could have survived. This was a time of primordial forces clashing against each other, every battle reshaping the land beneath them. We can still see the scars of these battles today. The fight could not last forever though. The Elementals were becoming tired, they needed rest. Each began crafting their sanctuary, a place where they could reign supreme and recover before launching their next assault. Over time, they grew accustomed to these sanctuaries, which we now call the elemental planes. They filled them with creatures suited to their element, leaving the material plane. They kept gateways, places where their element is particularly strong, but they no longer come to do battle on this plane.
Age of Divinity
Once the Elementals retreated to their sanctuaries, other beings came out from hiding and made their presence known. These were beings of intense power, though on a different scale than the Elementals. They were gods and devils. They spread across the world as it calmed from the terror of the Elementals. At first, they coexisted well, each one finding enough territory as more space became available, but this would not last forever. Soon each had expanded across the world and there was no more territory to claim. This was when the wars began. Gods and Devils fought brutally. To aid them in their battles they created creatures that would serve them, the worlds first mortals. Over time they came to love their creations, but the battles were so deadly on both sides that it soon became clear that victory would be empty at best. The gods and the devils looked at the Elementals and what they had done. They reached an agreement, both gods and devils would retreat, make their own planes. Their battle would continue, but not directly. Each would provide aid to their own creations, but they would reserve their full power for their own planes. The deal was made, the agreement signed, but when it came time for each of them to retreat, there were some that did not. Both sides became infuriated by these and joined together to lock them in a prison. They labeled them demons and cast them into an infinite abyss to rid the world of their presence.
Arcane Age
As the world calmed from the Age of Divinity there were some creations that began to amass more power than others. There were three distinct groups. The Shadow, The Fey, and The Dragons. Each pulsed with magic, some beyond their control. Dragons battled each other, shadows lurked and attacked the deity's favorite creations, the fey played with the minds of morals. They began to twist and corrupt the world around them. They taught the other creations secrets of how to control the forces that lingered. They laughed when the mortals began to play with fire too hot for them to handle and then offered to teach them how to treat these burns. Of the three, the shadows were considered the greatest threat. The gods began working together and began to banish these creatures to a separate realm. The fey helped them in this, but were keenly aware that it was only a matter of time before the same happened to them. To avoid being pushed into their own prison, they announced that they were creating a world of their own design. They made the Fey Wild, a world controlled by their own rules and free of the influence of others. As for the dragons, they were the biggest threat to each other. Their numbers were so diminished by the constant battle that the deities did not feel they were enough of a threat. This age left the world quietly, more of a fading out than the others.
Age of Mortals
This is the current age. Mortal creatures wield powers that remain from the other ages. Whispers from the Elemental age fuel the spells of Druids, powers granted by deities and devils help the clerics, paladins, and warlocks. Wizards still use the tricks learned from the fey and shadows to bend the natural world to meet their desires. Their cruel tricks live on in the form of sorcerers, unable to contain their powers.