NCsoft officially revealed the Ertheia today, showing the fleet-footed "mystical" people to the entire world. So who are the Ertheia? Let's go to the official press release for help on that: "While a lot is still unknown about Ertheia and the impact they will have on the world, it can be rightly assumed that they will be quickly drawn into the ongoing conflict in Aden." Wait, that's no help at all.
The Ertheia won't be released until next year to coincide with Lineage II's 10th anniversary in North America. You can watch the reveal trailer after the jump.
[Source: NCsoft press release]