Elves

In the beginning the Elven peoples were one. It was not until the event known only as the Decision happened that they split into the three different Elven folk that are known today; the Eladrin (High-Elf), the Noctrin (Gray-Elf/Drow) and the Syldrin (First-Elf/Wood-Elf).

The Birth of the Elves
The first children, the dragons, failed the gods and became everything the gods never wanted them to be - they were corrupt. It didn't take long for the gods to realize their mistake and some of the gods began to create other races to take up the mantle of Viru's inhabitants. The goddess Enzypia, the World Scryer, took it upon herself, as the goddess of knowledge and magic, to put her own creations into Viru. The Elves came to be in Enzypias own image and in their original form, looked like the standard Elves that Viru currently has.

But, like the other races that the gods created and placed into this world, they were almost immediately upon leaving their caves and becoming sentient beings, were taken into servitude or death by the dragons. The goddess needed to act, but the dragons had become too powerful for them to simply banish them from the world, they would have to rely on their new children. But like the other races, the Elves were very young and oppressed, they had yet to develop a sense of pride or bravery or even a sense of freedom and how it would be worth rising against their overlords.

Enzypia could not abide watching her children suffer under the claws of the beasts. She called to her children to escape and travel to the mountains to the east, then known only as Ironbone's Domain, named after the massive earth dragon known as Ironbone. Traveling to the northern edge of these mountains, thousands of Elves suddenly found themselves trapped against the edge of the foot of the mountains by the titanic dragon.

The Decision
Enzypia, desperate to save her children, quickly opened up three portals as her children, the Elves, were on the verge of either death or slavery. In her haste, the portals were flawed, quickly summoned to give the Elves an escape route. Deep in a cave behind the Elves they heard the call of their goddess, and the hum of these doorways. And the first Elves made their way inside.

Within, they found three portals to different places. At the time, already, the Elves had been split. Each had come from a different part of Viru and gathered here when their goddess called, the three tribes gathered here collectively and each one decided to take a portal.
 * The first portal, a bright white portal that let out a breeze and the smell of clover.  The first tribe stepped through.
 * The second portal was green and from within crickets chirped and wisps of magic blew through like dust in the wind.  The second tribe stepped through.
 * The third and final portal was purple and beautiful, fading in and out of darkness.  As they gazed inside they felt the promise of power and freedome.  The final tribe stepped through.

With each tribe making the decision of which portal to enter, and further to separate from one another rather than going through the same one, the Elves unknowingly changed their fate and started down a path that would alter the world and the Elven race forever.

The Three Degrees of Elven
When the modern world formed after the revolution was complete, it was clear that the fateful day had varying effects on each.

High-Elves, the Eladrin
Known as High Elves in your PHB.

First-Elves, the Syldrin
Known as Wood Elves in your PHB.

Gray-Elves, the Noctrin
Known as Drow in your PHB.