The Sidhe are a mysterious race of nimble-footed humanoids who still cling to their bulwarks in the wilderness. Of all the civilized races, the Sidhe are most comfortable with traveling in the interior, for they know how to move silently through the lush foliage and avoid the attention of the predators that lurk there.
They fought a war with humans a century ago over mere dogmatic differences in their theology. While the Sidhe wielded greater magic and could strike from the forests with ease, their numbers are few due to their very low fertility rate. In the end, the war was won by neither side.
As a looming threat grew out of the interior from the Brae, the Sidhe saw the ruin that lay ahead for them should the civilized races continue to war with each other. When the Sidhe leadership did not relent on their dogmatic attacks on the humans, a conspiracy of lower-level lieutenants staged a coup against the hardline old guard and killed them, effectively ending the war drums fueled by religious rhetoric. And none too soon, for within hours of the signing of the peace treaty, the Brae attacked, and it took both races to fight them back.
Sidhe use the default rules for elves in the Players Handbook.