Note: This is a simplified version of the history of the Forgotten Realms D&D setting.
While contemporary history is fairly well recorded, there is little evidence about how things started, only the eldest of the Divines even remember how the world looked in its infancy, but their memories and interpretations are often conflicting. The following account is based on revelations from different deities (see annotations for potential biases).
Creation of the World Edit
History began when the Overgod Ao created the universe in which all worlds reside (this likely references the Astral Plane). After this creation came a period of timeless nothingness, a misty realm of shadows that existed before light and darkness were separate things. Eventually this shadowy essence coalesced to form beautiful twin goddesses, polar opposites of each other, one dark and one light.
Selûne the goddess of Light and Shar the goddess of Darkness maintained a delicate balance. When Selûne discovered Fire and Warmth, Shar became envious of her sister and the war between Light and Darkness began (note that according to Evil deities it was Selûne who started the war, but most academics prefer to believe the Good deities). In the end, the twin sisters tore each other apart and from their essence a myriad of new deities formed (these are often referred to as the "Elder" or "First Gods"). Those which formed out of the essence of Light (children of Selûne) became the forces of Good while those that formed out Darkness (children of Shar) became the forces of Evil in the world.
While the newly formed deities continued the Eternal War, the battle between Light and Dark, Life formed out of the specks of lingering divine essence, from both Selûne and Shar. To preserve the newly formed races from the destruction of the divine war, the Overgod Ao decreed that the power of gods should (in part) come from their followers, thus forcing the warring deities to have an interest in the well-being of mortals. Ao has not shown any interest in the affairs of mortals ever since.
The Goddess of Life Edit
During one of their adventures The Faultless Arrow visited a temple of Vecna, the God of Secrets. From him they learned that the Gods have deliberately falsified history to erase all traces of the Goddess of Life. Her real name is unknown, but she was formed out of both Light and Dark. What made her special was her disinterest in the Eternal War. Instead she secluded herself on her plane and using specks of Light and Dark created Life.
Life flourished under her care and soon the power of her and her children rivaled the combined power of the other Gods. They grew envious of her and in a rare act of cooperation Good and Evil allied to take her down. She never anticipated the treachery of her siblings and was defeated by them. But before they could have struck the final blow, Ao intervened. He saved her, but also banished her to a prison to placate the others. To preserve her children Ao also decreed that the power of the Gods shall (in part) come from followers, thus making the Gods invested in the well-being of mortals.
For eon the Goddess of Life languished in her prison, slowly withering away, until only her Sorrow remained. Meanwhile the Gods erased her from history and changed the perception of mortals so that they will ignore the truth even if it is staring right at them.
This knowledge was granted to the Faultless Arrow from Vecna along with the power to retain these memories. But it is more of a curse than a gift as the party is unable to tell it to anyone else.
The 5 Great Civilizations Edit
Of the newly formed races the first to ascend and form a civilization were the saurians. Their civilization was short-lived though, their empires crumbled, their culture was lost. Most of their descendants reverted back to their primitive past (likely a reference to the lizardfolk and troglodytes) while some continue to squat in the decaying ruins of their once great ancestors (reference to the nagas who live in their ancient cities and still have some form of civilization).
The second and greatest of all civilizations was that of dragons. Dragons dominated the surface world, claiming vast areas of territory and battling each other for land, mates, and status. Their pride became their downfall as they failed to unite once the lesser races mastered magic. They still remain influential, but there is little left of the once mighty dragon empires.
The third great civilization was an aquatic race that eventually fell to the onslaught of the barbaric merfolk, tritons, and krakens. (There is very little detail about this civilization, and most scholars speculate that the third civilization was actually the interplanar Illithid Empire, a fact that Good deities are reluctant to include in their teachings. The Illithid Empire fractured due to a massive slave uprising, likely facilitated by these gods.)
The fourth great civilization was created by the sylvans who lived on vast forests in perfect harmony with Nature. It is believed that their civilization fragmented after a great plague, created by a draconic or demonic power. Their descendants are the fey.
The last great civilization is that of humans, elves, dwarves and gnomes, the one we live in today. (Sources conflict on which is the dominant race, each has a convincing argument: the gnomes discovered magic, the dwarves created industry, the elves were the first to develop literature and culture while the humans are the most numerous and they rule most of the land.)