At the end of the Divine Age, the gods tore the world of Enthilon apart. This was a result of their anger and jealousy. Some say it was just a cataclysmic temper tantrum. They wanted the races of the world to suffer for rejecting them so they ripped Enthilon apart and set the pieces floating around the molten core. And then they left.
Most of the sentient races, after recovering from the shock of their world's destruction, were glad to have them gone. After all, they (led by the Elves and the Humans, although there has always been heated debate about exactly which races were involved) had asked them to leave. They had grown tired of the constant meddling in their affairs. They were tired of being subject to the whimsy of the gods. They were sick of being the pawns in their constant struggle for power.
Imearth is one or the floating continents created by the cataclysm. Its inhabitants recovered quickly and began rebuild what was left of their world. They also began to excel in the use of magic. This was power that had nothing to do with the departed deities. This was a power of their own. This was the Age of Magic and it was a time of great accomplishments of all kinds.
The Age of Magic lasted for thousands of years. Towards the end of the age, though, things began to deteriorate. Great storms would coalesce out of thin air. The ground would tear into great fissures without warning. Mountains would collapse and lakes would boil. Thus began the Age of Chaos.
Chaos and madness reigned. The sentient races found themselves living in a nightmarish world. Time ceased to have meaning.
There were a few, though, who fought. A few who sought to find an answer to what was happening to Imearth. The conclusion that some of them came to was that the Lost Gods had held reality together. So they called for the gods to return. They called and called as they fought to hold onto what was left of their minds. It can not be told how long the Age of Chaos lasted but eventually most of the gods did return. Slowly order was restored and the races of Imearth rejoiced.
The inhabitants of Imearth were ready to accept the gods rule but the gods declined to take control. Some believe this is because the gods (most of them, anyway) had matured in the ages of their absence. Others believe that there is some higher power keeping them from taking any but the smallest of active roles in the affairs of the world. So the gods stand back, relegated (or choosing) to using their followers to further their agendas.