The Evantari consider themselves superior to all other elves, and perhaps to all other living creatures. The Evantari consider themselves the Chosen People—those who were meant to lead the others to their eventual ascension. When the other elven cultures rejected this, they severed ties and took residence high on the Evantyr Plateau, closer to the sun that they so love.
The high elves are entirely disconnected from other cultures. The only stories I’ve found of anyone seeing the Evantari first-hand in recent years are occasional sightings of them traveling on some unknown task, and always from a distance. The men of Mideon, who guard the border forts and keep the dark elves in their banished lands, have said that they occasionally see bands of Evantari traveling North in hunting parties to bring wrath down upon the dark elves.
During the Time of Servitude, the Evantari were regarded highly by the Eldar. They often served as house servants, and many became military commanders over the Orovari. When Kaldrath lead his uprising against the Eldar, the Evantari took up arms to defeat their renegade brethren.
The Evantari believe that they were the Chosen of Tanthias, and that the Eldar were the direct descendants of Tanthias and Arias. They served their masters with legendary zeal. They fought against the Orovari, and for a time, the Orovari were driven from the cities of the Eldar. But Kaldrath had aid from dark places and summoned the Orlocks—fierce fighters from a distant world. Lead by the Mordrei, Kaldrath’s army focused on one major city after another, and each city fell. Not satisfied with mere victory, Kaldrath’s enemies were utterly destroyed. Survivors were tortured with unimaginable creativity and brutality. Their will was crushed, and soon they were begging to join Kaldrath. And so with each city that fell, his army grew.
By all accounts, the Evantari fought bravely and ferociously, but soon they had to face the inevitable. Kaldrath, after capturing the last stronghold of the Eldar, asked the elves to bow before him. When they refused, the Evantari were bound, tortured, and enslaved. The soldiers they once commanded were made their overseers.
The high elves were forced into submission, but their will was never broken. After a time and a great deal of planning, they revolted. The initial uprising inspired many of their elven brothers and and sisters to join them. The high elves took to the front lines, throwing themselves at their captors with a ferocity that frightened even their allies.
When Kaldrath was captured, the Evantari sought to execute the traitorous Orovari, but the other elves refused. Thus began the rift between the cultures that persists to this day. The high elves assumed rulership of all elvenkind, but found their new subjects less than cooperative, having tasted freedom. So after Kaldrath was imprisoned and the Orovari driven north, the cultures separated and the Evantari made their home in Evantyr, where they have lived ever since.