Lore Dump: Creation
In the Beginning
Before mortal races treaded the multiverse, the gods floated alone in the primordial froth of the Elemental Chaos. Together, they began carving up the universe amongst themselves to consolidate their own identities; most drifted far from their enemies and near to their allies, creating the planar poles. Others sought to remain travelers in the rapidly evacuating expanse of the multiverse. Once the realms of the rulers were cut from the planar fold, the remaining elements began to congeal in the center: the Material Plane. Around it solidified the shell of primordial leftovers which bar the exit from reality to most mortals. The gods were once again eager to slice up this new territory, but found themselves unable to manifest directly unto it. Instead, they could only influence: thus began the scramble to rule the world.
The Realms of the Deities
The gods saw it fit to shape their own lands to their preferences: the civilizations within, or lack thereof, are directly influenced by their desires.
Ilunae watches over Elysium: the fields of gentle rest and eternal comfort.
Gynther provides for the Beastlands: a wilderness of unending bounty.
Lyverosia rules Arborea: the glades of passion and freedom.
Vetrus commands Ysgard: a domain of heroes and champions.
Koh has Limbo: an ever-changing landscape of the forgotten.
Ostyryx created Pandemonium: the depths of deafening air.
Yntiago hoards the Abyss: an endless pit filled with stolen souls.
Nekrecta built Carceri: either a prison or a zoo, depending.
Gruumsh conquered Hades: gray wastes where nothing may stand.
Gyrisil holds Gehenna: a bleak plain where hope has died.
Tiamat presides over the Nine Hells: the realms of the wicked.
Kurtulmak dominates Acheron: an infinite, brutal battlefield.
Alman controls Mechanus: where chance cannot exist.
Garl Glittergold walks Arcadia: peaceful, idyllic kingdoms.
Avin guards Mount Celestia: the seven courts of heaven.
Bahamut sleeps in Bytopia: the elusive paradise.
Sardior explores the Astral Sea: the gateway between worlds.
Talenturra plays in Aura: the elemental plane of air.
Nirasman experiments with Aqua: the elemental plane of water.
Groamuth refines Terra: the elemental plane of earth.
Auron tempers Igna: the elemental plane of fire.
Hoaketh lurks in the Ethereal Plane: the veil between life and death.
Yiddia stalks the Feywild: the vast forest that is both cruel and kind.
Noct haunts the Shadowfell: a void that seeks and devours light.
Race of Races
When the deities set their eyes upon the Material Plane, they saw that it was unlike anything that they had created: law, order, good, and evil all coexisted together in a delicate balance. However, it was devoid of sentient life, for only beasts and plants were present. The first to make their mark upon the land were Groamuth, Ilunae, and Vetrus. Groamuth crafted the first dwarves in the Calmere Mountains, imbuing them with the talent to create from the earth's resources. Ilunae created the elves within the Exiles and gave them above all else, grace and the ability to shape the environment to coexist perfectly. Vetrus branded the Western Expanse with his own creation: the proud giants. These three races grew to feud with each other, all eschewing the practices of the others equally. The elves had a distaste for the dwarves and giants, for they would bore holes and chop trees to sate their desires. The dwarves thought the elves and giants aspired for perfection not befitting of mortal creatures. The giants looked down on the pathetic, lowly achievements of their diminutive neighbors. And so the first races warred constantly against each other alone for two thousand years, until more deities' eyes descended to the Material Plane.
Whilst the elves, dwarves, and giants fought in the west, Hoaketh, Yiddia, and Gynther brought in their own creations. Hoaketh created the aarakocra in the heights of the Platinum Peaks whom were charged with guarding the reliquaries of the multiverse. Gynther made humans within Yiddia's Cradle to bring together all things as in a harvest. Yiddia, seeing Gynther's encroachment, tempted the humans with mastery over the elements, to which some happily agreed, becoming the first genasi. As the human civilization spread over the Platinum Peaks, a great calamity would occur.
The City of Doors
Sigil was once the stronghold of the aarakocra; it sat upon the highest peak of the world, close enough to the heavens to nearly touch them. Within Sigil's boundary were kept, like a museum, relics that could undo the multiverse if they fell into the wrong hands. And into the wrong hands one fell. An aarakocra thief stole the Key of Veles, an artifact against which no lock can defend. In order to flee from his pursuers, he opened a planar portal to the Astral Sea and escaped into the vast expanse. He did not close the door. By the time his treachery was discovered, creatures that do not belong in the Material Plane had already leaked through: that which is called "aberrant." The aarakocra faithful to Hoaketh begged for her mercy and assistance, while the rest fled Sigil and were cursed to lose their most prized trait. Thus, the first kenku were made. Hoaketh entreated the assistance of Bahamut, Sardior, and Tiamat, all of whom came to her aid, on the condition that their own creations be untouched by Hoaketh's binds. The conditions were begrudgingly acceptable, and the sublime dragons, the divine agents of their masters, descended to the Material Plane to protect it from utter ruin. While the battles between the divine and primordial creatures raged, the rest of the gods staked their claim in the Material Plane, reaching far beyond the doors of Sigil, which had become fragile to the point of shattering across time and space.
Garl Glittergold graced the world with gnomes underneath the Platinum Peaks. In retaliation, Kurtulmak introduced the first kobolds into the Dragon Queen's Mountains. Ostyryx propogated the yuan-ti in the Tanaba Jungle. Avin made the tritons in the depths of the Bay of Ilunae. Gyrisil made goblinoids to raid and ransack the whole east, and Yntiago cursed a few unfortunate humans with the first tiefling children. Gruumsh placed orcs in the Northlands while Talenturra peppered the Western Expanse with halflings. In the end, all of the gods made their own mark in the many sentient races, but the immortal dragons that had been summoned to fight the aboleths and their kin tired of the war. Eager to return home, the sublime dragons created dragonborn with the permission of their superiors and departed from the Material Plane, their work still unfinished. Thus, the creation of the races of the world was finished, and Sigil remains somewhat in the Material Plane as proof of those events.