Countless eons ago, Mahadeva, King of the Gods and Creator of the Whorl, set it adrift in the Endless Void, filling it with the other gods and his favored mortals. It is said that he created the Whorl as a great vessel to transport the blessed across vast time and space to a great paradise. For many generations, humans thrived under the benevolent gazes of the gods, who were in turn kept balanced and in check by Mahadeva, Lord of Beginnings and Endings, Birth and Death.
While Mahadeva lived and ruled, only Humans lived in the Whorl. Eventually, however, Mahadeva's eldest son, Surya, God of the Sun, became jealous of his father's power over creation. After all, was he not the Sun, the source of all energy, light, and life in the Whorl? Surya gathered thousands of his most faithful under his high priestess Aranyani and they enacted a great ritual, changing them into the first Elves. Surya was proud of his work. He felt he had improved upon humanity, creating a race of deathless immortals, noble and radiant and wise. His father had other opinions.
Filled with wrath, Mahadeva insisted that Surya change his followers back to ordinary humans. The King of the Gods was affronted at such drastic changes, particularly the grant of immortality. Such a people, he contended, would rapidly fill the Whorl, altering the careful balance of life.
Surya refused. Anger and argument escalated. The gods began taking sides. The debates and rancor lasted most of a year, it is said, before first blood was spilled.
The War in Heaven and Earth, also known as the Godswar, raged in The Realms of the gods as well as within the Whorl. Mahadeva's other children were split in their loyalties. Mahadeva's second-eldest, Indra, Lord of the Skies, fought fiercely in support of his father while Varuna, Lord/Lady of the Seas, supported Surya. Yama, Lord of the Underworld, as was his wont, did not participate (openly) at all. Surya was further aided by his wife Ratri, Goddess of the Night, and his son Ravana the Trickster. The twin goddesses of Fortune and Misfortune Lakshmi and Jyestha, also came to Surya's side as did Lakshmi's wife Durga, Goddess of Conflict, who in so doing became the Goddess of War.
The War pulled in people on all sides and great battles were fought throughout the Whorl. Mahadeva suspended the Law of Death and those who fell in battle on his side were revived almost instantly. Surya saw what his father could do and attempted the same, although to lesser effect. His own revived troops were not fully alive once more, but were still capable of movement and combat. They had the added benefit of terrifying their foes with their rotting flesh and pale countenances. The lesser gods began augmenting and twisting the humans fighting for them in their own ways. Durga and Lakshmi joined their power to create the first Dwarves while Ravana twisted his followers in even more extreme ways creating Orcs, goblins, and assorted other Monsters.
The War would have been short indeed had Mahadeva's own wife Parvati, Goddess of the Land and of Life, joined in his support. She could not bear to fight with her sons, however, and stayed conflicted and neutral for most of the War. Finally, after great struggle and expenditure of personal power, Surya entered his father's realm and destroyed him. This started the Endless Day, when the sun stopped moving across the sky. The War paused as all sides reeled at the horror and extremity of what Surya had done. Newborns fell from their mothers without the spark of life. The dead lingered, trapped in rotting bodies. Surya, drunk on his victory, struggled to consume his father's essential nature, the language of his power, for his own but found himself fraying and fracturing. Then he was betrayed.
Aranyani, Surya's high priestess, first and Eldest of the Elves, renounced her god. With passionate rhetoric and consummate charisma she led fully a third of Surya's elves away and into the service of Parvati who, in Aranyani's estimation, was the only entity capable of absorbing the language that embodies and binds Mahadeva's power and authority. She was not the only defector. Horrified at how far Surya had gone, and the disaster that was unfolding, all the other gods except for his wife Ratri and son Ravana left Surya's side, either joining Indra and Parvati or standing neutral. Even with nearly all the gods united against him, however, Surya was fat on his father's corpse, glutted on raw power. Although he could not absorb it without going mad, he was imminently willing to try.
Parvati called upon all her children and fellow gods to join the language of their power with hers and from these unions she seized the power of Birth from her dead husband and thus gave birth to the Ten Great Dragons, immortal beings of immense power. These Dragons in turn modified hundreds of mortals creating the first Dragonborn. With their potent support, Surya's power and his armies rapidly crumbled. Recognizing that the Whorl would die without the power of the sun, Indra and the other gods did not slay him. Instead they stripped Surya of his authority, bound him in great chains made out of potent words, and set walls and safeguards about his heavenly realm, imprisoning him yet siphoning his power so that the sun would continue to burn. Those of his elves and other supporters who still stood loyal were cast into his realm with him, to suffer eternal imprisonment in the heat of proximity to their chained Lord.
Having seized the language of birth with the creation of the Dragons, Parvati next seized the language of death from her husband's corpse. The strain split her in two. Parvati / Kali, the goddess of birth, life, and death, was no longer stable enough to rule over the Whorl as her husband once did. Her second-son Indra seized the mantle of King of the Gods, although the title does not rest as securely upon him as it did his father, and the other gods constantly strive and scheme and plot behind his back.
Indra, with the support of his mother and his aloof, neutral brother Yama, turned his attention to judgment of the combatants. He gave to Aranyani and those elves who joined her against Surya a choice. They could either accept mortality once again or ascend to Parvati's heavenly realm as stewards and caretakers to aid the fractured goddess in maintaining herself. Aranyani and many of her followers chose to keep their immortality in Parvati's heaven, a place of endless life and secretive forests sometimes called the Feywild. Those followers of Aranyani who chose mortality became the wood elves.
As for those gods who had fought beside Surya, Yama prevailed on his brother Indra to be merciful. Too many had died, and he feared the effects of his mother's sorrow, not to mention the effects on the Whorl, should they be executed. Those who abandoned Surya before the end were diminished, but otherwise let free. As for Ratri and Ravana, they were stripped of their divinity, diminished, and confined to physical (albeit undying) forms. They lurk in the darkness, consorting with the monsters and creatures they created, plotting their revenge.
The Whorl would never be the same. The Great Dragons went to sleep with the promise that they would awaken to preserve the Whorl should war once more erupt between the gods. With this powerful disincentive, the gods have taken to intrigue, conspiracy, and the manipulation of mortal pawns to push their agendas. Without Mahadeva, each of them holds some degree of hope that they might rise to supplant Indra as Parvati's consort and King (or Queen) of the gods. Indra does not have his father's power to forbid the creation of new races, and so a number of the gods have taken to tinkering themselves, creating new races from their devoted followers. The Whorl has become a far more diverse place as these new races breed true, not all of them choosing to adhere to the faiths of their forebears.
Surya’s Prison is not infallible. His power must still flow to the Sun, and his secret devotees have learned the language to open small flaws of logic to his prison. Some of his powerful imprisoned followers can, with arcane aid, slip their chains for short periods, causing havoc as demons or devils. Others have escaped entirely, being reborn in the Whorl as the demonic Tieflings, although after the first few generations in the Whorl, their loyalties to Surya are not as guaranteed.
And so in this modern time, some millenia after the War in Heaven and Earth, you can find High Elves worshiping Chinnamasta alongside Gold Dwarves and Dragonborn, one's birth not necessarily indicating one's devotion. Some nations of the Whorl limit the races they permit within their borders while others are more cosmopolitan, seeing the benefits of harnessing the diverse skills of diverse peoples.
And the gods plot and scheme, and the Great Dragons slumber, and the Whorl sails through the Endless Void, presumably still on course for Paradise.