Timeline

The Primordial Age

0000 - Primordial Cataclysm. Primeval entities walked the planes, creating destructive waves in their wake that formed the planes as we know today. Massive eruptions from within the core, huge flooding storms and ever-flowing rocks slowly carved out the Material Plane. When the destruction subsided, all that was left were newly formed planes of existence, stemming from all forms of natural occurrences. While many believe it was the Greater Gods that did this, there is evidence to believe that many of the planes formed through natural, destructive means. However, the natural elemental planes and the Material Plane had no barriers at this time; it was continuous primordial events that continued to shape the Material Plane every hundreds of years.

0030 - Precursors. Highly intelligent, sentient entities known as the Precursors travel to the forming Material Plane and Elemental Planes. Fleeing from an ancient enemy, the Precursors start the creation of life; a single spark to get life on this planet going. Other entities follow suit. The Precursors eventually leave, but stay within the solar system to watch their garden grow. The other entities that remain on this world would eventually become known as The First Gods.

0100 - Divine Light. The First Gods continue the work that the Precursors left unfinished. These entities were all powerful from an ancient plane known as Celestia. These Gods continued to breathe life into the planes, each dividing their task among themselves. The First Gods created primeval animals, plants, and eventually, the first humanoid. These humanoids looked nothing like our "humans" today, as they were modeled after the Precursors. Overtime, evolution would be had, and the primordial creatures in the beginning would evolve to more modern versions.

The First Gods did battle with massive primordial entities, such as Elemental Titans that continued to break and tear the realm apart. As The First Gods destroyed many of these disruptive titans, some of these Gods fell in battle. Their bodies and energy would empower the first mortals, giving them clerical powers. This energy would also spawn new gods under them and slowly form a massive pantheon within the plane of Celestia.

The Celestial Age

1000 - Divine Birth. As life was blooming on what is now known as The Material Plane, as it was created from all forms of materials during the Primordial Age, many of The First Gods decided that they must spread themselves among the lands and continue to fertilize life. They started taking large amounts of their power and creating other gods with it, as well as using their life to birth more creation. From this, many new gods were given life, and were given the responsibility to watch over The Garden, or The Material Plane. Some of these gods that were formed were Sarenrae, Pelor, Ehlona, Celestian, The Star Queen, and Myrkull.
As pantheons continued to be created, each God was given a "portfolio" of power that was passed down to them. That portfolio would dictate what they would have dominion over within the world. All the Gods in this time were busy with the creation of life, and soon the first humanoids would evolve into two types: The Lumair (Elves) and the Romair (Orcs).

1200 - The Gates. While life was still being born, and the first humanoids starting creating fire and learning to survive, the Gods saw chaos still within the planes. There was no protection as of yet from the Elemental Planes, which was the current biggest threat to destroying all that was created. The Gods came together and decided to create incredibly powerful barriers between these planes of existence, called Divine Gates. These gates would prevent any free travel between the planes, thus stopping any destructive elemental energies coming to harm. The Gods also decreed that some would go and oversee these planes. While their power was create, the plane that they oversaw was much stronger and much older than they, thus creating and transforming some of these gods into Gods of the Elements.
Other Gods would place themselves in these newly forming Outer Planes; some of these planes were being created while others were manifesting into reality from the undiscovered magic of the realm. These planes would turn and meld these Gods into different forms.

1500-1550 - Light and Dark, Good and Evil. While The Material Plane was complete, the Elemental Planes were sealed off as well as other planes within the realm, a new type of God was forming from the remnants of the First Gods. One of these Gods, who mysteriously had no divine energy flow out of them to create life, had cast a massive shadow on one half of the world. The Lumair and the Romair typically avoided this place, but it offered cool climates to those that did live within. This shadow started to take form, and any that lived within this massive shade began to lose color and vitality. For many years, this shadow began to plague the world with vitality-sapping energies, for those that came near and/or lived within. The Gods in Celestia took notice and collectively banished the shadow, as well as the body of the First God that it had been clinging to. The shadow began to take form from this banishment, and as it grew in power, those that were unfortunate to be banished as well started to die. When it finished its transformation, this shadow became known as The Shadowfell, a plane of eternal darkness and death.
Limitlessly spawning from the corpse of this god were the first undead, those that were unable to escape being banished. From this corpse, Gods of a different breed began to take form; Gods with darker intentions, spawned by lifeless energies from this plane.