To populate Terrania with Life, the Primordials fused their energy to give birth to Silvanus, god of Nature, who was instructed to create all manner of flora and fauna. Among these myriad of creations came ancient civilized beings, from whom you and I are descended.
Proceeded by: The Age of Darkness
The Age of Creation includes all of history prior to the events leading to the Age of Darkness, as well as the prehistoric events before it during which Silvanus created the world and all in it.
The Age of Creation is an inverted calendar - AC 0 refers to the transition into the Age of Darkness, and large numbers are further in the past. The earliest artifacts have been dated back to approximately AC 8500.
Written records emerged at different times, depending on when various races developed their own writing systems. Historical accounts and mythic tales are indistinguishable from this time period.