Are elves native to Faerun/Toril, or are they immigrants from elsewhere (like the Feywild)

Question

Where did the D&D 5e elves come from? (In-universe sense).

Based on some comments under this answer, this map of the Feywild, the fact that elves have Fey Ancestry (see PHB), and the following entry in the Monster Manual:

Fey are magical creatures closely tied to the forces of nature. They dwell in twilight groves and misty forests. In some worlds, they are closely tied to the Feywild, also called the Plane of Faerie. Some are also found in the Outer Planes, particularly the planes of Arborea and the Beastlands. Fey include dryads, pixies, and satyrs

I am moved to ask: Are the elves of Toril/Faerun native to Faerun or are they (originally) immigrants from the Feywild? (Or even from somewhere else?)

The lore on elves seems to have gotten muddled over the years, to say the least. What I am trying to clarify -- now that I am immersing myself in the dragon/giant ur-conflict (5e lore) based on the Storm King adventures and Volo's Guide -- is if the elves are a native race in Toril/Faerun or immigrants, even refugees, from another world or plane. (Evermeet (p. 72-73 SCAG) across the sea further complicates this question for me. The published material in the DMG covering the eladrin hints at a Feywild origin).

I have big holes in my understanding of how Forgotten Realms lore has morphed over the years. I have read/bought very few FR books since the 1990's, and did not get 'into' D&D-3.x and its lore, and got into 4e not at all. Most of my FR lore is at least 20 years old unless it is in the 5e form.

Answer Criteria:

The answer I am looking for must address the current Lore baseline, which is Dungeons and Dragons 5e, Forgotten Realms.

Material that reaches back to previous editions is helpful for how elves "fit" in the Forgotten Realms, and perhaps how they have been refit. While I am looking for the 5e Lore answer, where 5e Lore is silent material / lore from a previous edition will be useful, as long as which edition it comes from is specified.

Answer 1

5E Realms lore does not specifically address this. 4E Realms lore, on the other hand, does. Their exact origin is subject to some debate, even among the elves.

Collectively, the elves are known as the Tel’Quessir⁶ ("The People"), a title that encompasses Eladrin, Wood Elves, High Elves, Sea Elves, and so on. It is 'widely accepted' that the Tel’Quessir are native to the Feywild¹. It is believed that they first immigrated to Abeir-Toril over a hundred millenia ago, while the exact date is uncertain it is believed to have been prior to −24,000 DR, with some manuscripts indicating it was as early as −30,000 DR, the same time in which dragons were setting up their empires (Note: Source on this is from AD&D)⁴. The Wild Elves were the first to arrive.¹

The exact origin of the Elvish race is subject to some debate. Some ancient manuscripts suggest that they were the result of a battle between Gruumsh and Correlon that occurred in the Feywild. During said battle, Correlon was injured and his shed blood became the Eladrin.². Other types of elf, not liking the superiority this implies in that the Eladrin are the first and 'purest' of elves, disagree with this theory³. Another theory postulated is that since the Feywild tends to be a 'reflection' of the Prime Material Plane, and thus produces creatures that are echoes of creatures from the Prime, it is also possible that the Elves are one such echo... though what, exactly, they would be an echo of is uncertain¹.

Perhaps also worthy of mentioning is the current in-lore explanation for how the Feywild (also known as Faerie) is treated according to current lore. The Feywild was created as it exists today, a 'lighter' echo of the Prime Material Plane. It was made by Primordials in the far distant past, before recorded history begins.⁵

For a while, the Feywild existed alongside the Prime and interaction between the two was common. But, at some point in ancient history, the two drifted apart and travel between them became increasingly difficult². This is the explanation for why, in prior editions of D&D, the Feywild didn't "exist" in the Forgotten Realms. It was out there, you just couldn't get to it.

The Spellplague (the event that 'kicks off' 4E in the Realms) changed that, reshuffling the cosmology to drag the Feywild back into close proximity, and placing it in the accessible location it resides in today⁵.

Checking through published 5E Realms material, it does not contradict any of this... the 5E Realms cosmology is essentially the same as the 4E Realms cosmology, and the lore established within 4E is considered to hold true in 5E, except where directly overridden. And even then, the changes are usually justified in-lore (such as the array of gods and goddesses getting rejiggered due to Ao meddling with them).

The primary lore sources we have in 5E Realms are the Sword Coast Adventurer's Guide, the DMG, and published adventures. None of these go into detail on the origins of the Elves, or even on the specific nature of the Feywild... thus we may assume the lore of older sources hold true.

Sources

¹ Brian R. James and Ed Greenwood (September, 2007). The Grand History of the Realms. (Wizards of the Coast)

²Bruce R. Cordell, Ed Greenwood, Chris Sims (August 2008). Forgotten Realms Campaign Guide. (Wizards of the Coast)

³James Wyatt (December 2007). Dragon 361: A Fractured Family. Wizards of the Coast.

⁴Steven E. Schend and Kevin Melka (1998). Cormanthyr: Empire of the Elves. (TSR, Inc) NOTE: AD&D source

⁵Dungeon Master's Guide 4th edition. (Wizards of the Coast)

⁶Kim Mohan ed. (2015). Sword Coast Adventurer's Guide. (Wizards of the Coast)

Answer 2

Quick answer without specific sources (this is 1st/2nd Edition material): -

During the Time of the Dragons (between -30,000 to -24,000 DR), the Fey in the Realms were actively opposing the dragons and opened gates to the Feywild to bring elves into the Realms in the belief that the elves would be able to help defeat the dragons.

This was altered for 4th Edition as follows: -

Taken from http://the-bestiary.wikia.com/wiki/High_elf_(Forgotten_Realms)

High elves, unlike wood elves who appear conspicuously absent from the Feywild, are not in fact native to the Prime, having emigrated to Toril from the realm of Faerie during the Dawn Ages. This migration started circa -27,000 DR when the fey opened gates from the Faerie realm allowing large numbers of green elves (who later became the true elves), avariels, and lythari to immigrate to Toril. Further immigrations to Faerûn occurred around -25,400 DR, when the sun elves and moon elves, the modern variants of high elves, first arrived. These early settlements were early enough that when Abeir-Toril was split into two, elves and high elves ended up on both worlds.

Through the efforts of these early high elf settlers the Time of Dragons would be brought to an end and the First Flowering of the Fair Folk would begin, resulting in the temporary dominance of wood elves and high elves over all of Toril.