Chronicles of Khaldun: Crux of Eternity
The insular elves of Nainimdul do not often traffic with outsiders, although their reasons are unknown (most people suspect it has something to do with the goblin slaving rings that occasionally stalk the forest).
Whatever the case, only elves are welcome in Nainimdul, and then, outsider elves are welcome only reluctantly. The occasional half-elf has been known, but they are typically treated with scorn and derision. The elves of Nainimdul also segregate by sex — only the men are allowed to be Woodwalkers, the rangers who protect the surrounding forest (women are more likely to learn magic, although men are not prevented from doing so). Some surreptitiously train women, but any who are so trained are typically cast out by the tribe.
The cause of the strange superstitions in Nainimdul are unknown, but one hopes the Greengrove Council has good reason for doing so.