The Aen Seidhe are elves who came to the Continent on their white ships before the humans appeared, unlike the Aen Elle who inhabit a completely different world than the one in which their counterparts reside.
However, unlike their counterparts, the Aen Seidhe began to fall to human encroachment as, while they lived long lives, they didn't repopulate as fast as humans and only young elves were fertile. Nevertheless, they continued to fight while their cities fell to human control. On seeing that humans built on top of these elven cities, the elves began to destroy their own cities as they retreated to try and prevent them being used by humans.
By the early 1260s, where they once controlled most of the continent, now the Aen Seidhe had neither a country to call their own nor a true ruler and were all but scattered across the land, with some in the North banding together as the Scoia'tael and using guerilla warfare to combat discrimination they faced from humans.
- The Aen Seidhe are likely based on the light elves of Norse mythology and the Seelie Court of Fairies in Scottish folklore. Their name is also inspired by the Aos Sí, older form of aes sídhe, a nation of faries and elves in Irish Mythology who lives in a parallel world from the humans.
- In The Lady of the Lake, it's stated that a Door opened up and the elves departed the known world. It's unclear though if this means every Aen Seidhe left or where they ended up.