Dark prophecies predicted the fall of the ancient races and the ascension of the young races.
The prophecy was handed down by the High Prophet Ederling, Kapil Swapnil, who who went into exile after revealing the prophecy. It would be later discovered that the high prophet had seen that in the next 1500 years that the Ederlings would be the cause of the downfall of the world.
The Dragons retreated from the world and were not seen again till modern times. Their primitive children became the dragons the young races knew of; chromatic and metallic dragons.
The Giants saw their race dwindle into more primitive beings until none of the Ancient Giants remained. It is rumored that the race made preparations towards saving the world.
The Ederlings discovered a group that was resisting the change of power. This corruption had led them to becoming Darklings. The Ederlings before they faded away dealt with the Darklings in a manner that seemed permanent.