When the gods were young and before the Icuriana raised their temples and great palaces in the West, the great elven nations dominated the Cunaerai. Their magics shaped the land to their will, and they made compact with Moon and Faerie to bolster their lordship over the land, the air, and the sea with the luminous power of the sky and the fey. Unknown to most of the mortal races, a great calamity befell the elves in the age of the Adversary’s rise. The very magic they bound to create their unassailable domains became the unquenched flame by which their cities and their people were consumed. As the goddess known as the Green Mother and her children were reborn into the Cunaerai, the natural world that the elves had saddled to their will were unleashed in unbridled anger to take back the power of the Green. Thus the great and mighty cities and cultures of the elven lands were overrun by wood and wild.
Today, the elven nations remain in ruin. Each forest bearing the ancient names of the elves are the overgrown remains of bygone elvish fastnesses, their borders preserved and guarded by both lingering elven magic and the flooding tide of Green commanded by the power of the Mother and other gods of old. The places of elegant beauty they once ruled are now untamed, verdant areas of tree, hillock, and spirit. As for the elves, they are a haunted people consumed by the past. They have ever been slow to adapt to the newness of the world, perhaps due to their near-immortal nature. They live in the ruins of their forebears, some ancient few even remembering the great calamity which befell them several millennia ago. The lands of the elves, while overgrown, wild, and rife with the magic of the old gods, nevertheless remain hostile to those the elves consider enemies, and so the overwhelming majority of this race will never leave these vast, protected places. Those non-elves who venture into elven lands do so at great peril, but riches and ancient places entombing the magic of a lost age are said to await those who do.
Elves who maintain ties to their ancient grandeur, civilization and history are known collectively as high elves. They live in the forest realms that still bear the old elvish names: Aywhel’leen, Ehaindel, Savohei, and the great elvish realm of El’enethwhen. These lands are elvish nations in every sense, with borders, once-graceful cities and towns overwhelmed by the Green, learning and unified culture stretching back through the past ages. The mystical learning of thousands of years still rests in the ancient places of the high elves, diminished by the whims of Time and the decline of this once-great but still proud people.
There are those elves who have forsaken the ancient forest realms of elvendom and turned their backs on the ancient learning, saying it has brought only grief and doom to their people. They view the high elves as having lost their way or abandoned the true calling of their blood and the primal magic of wood and wild. Known as wild elves, they have retreated from human and high elven lands and wandered deep into the enchanted woods of the Cunaerai, living in harmony under the sun-dappled leaves and cold starlight of the wildlands. Mischievous, sometimes dangerous, but above all free, these wild elves have allied with the Green and coaxed the trunks and boughs of the great ancient trees of the deepest forests to carry and protect their villages and ring the glades that constitute the wild elf realms.
In the Fourth Age, the ancient elven kingdom of Ithwendel on the eastern shores of the Sea of Crowns was brought low by the fanatical followers of the God who would be King. As the ancient forest of this once-great kingdom burned to ash, the elves there besought the Courts of Summer and Winter to spare them and deliver them into the lands of the Faerie. They were spared, though forever changed, by this deliverance, now bearing the markings of their pact with Faerie – alabaster skin tinged with cerulean, pale white eyes, and white hair that glistens silver in the starlight. They are called the ghost elves — the Eladrin. Spread across the Cunaerai, they are elves drifting without a homeland – their strange pact with the Fey Courts make them unwelcome in the lands of the high elves, though the reasons behind their exile is unclear. Rumors persist that the Mage Queen of Ja’Shien has recently welcomed a large clan of ghost elves into the Ta’Hai’een forest bordering Kur’Shien along the L’Ehenna River and encouraged them to settle there. Even more strange – the Heirophants of the Circle have reportedly roused the power of the Green to restore the wooded boundaries of the ancient Ithwendel homeland. Now called the Amber Forest, this enchanted woodland slowly encroaches on the borderlands of the Holy Kingdom.
Finally, there are the high elves of Dunlundel forest, now the Wretchwood, who were changed by the hungry shadow of Malapheme. Whatever these elves once were, they are now cloaked in Night – the sun they once frolicked under now burns their red-limned eyes. A battle now constantly rages within them between the consuming shadow and the tempering moon. They are now called the drow, the dark-elves, unwholesome kin to their elfin brothers and sisters. Some have given over completely to the darkness that swept like a wicked tide into their lands and their hearts. Most, however, seek to battle that which slowly consumes them, and so the drow gentleness is tempered with cruelty, their mirth with sullenness, and their joy with hatred.
PC Elves will most likely be that rare breed of elf which because of obligation, hardship, or wanderlust, have passed into the lands of humankind. Half-elves typically hail from those hamlets, towns, and cities near elvish lands where trade is conducted between elves and humanity.
Players may choose to be high elves, wild elves, ghost elves (eladrin), or dark elves.
Statistics for Eladrin are found on page 286 of the 5e DMG.