Originally Posted by
Vyrerus
I lean towards Garleans being aliens unique to The Source or a post Sundering race unique to the planet that cannot manipulate aether because they are not tied to the planet as it originally had been. They could also be genetically engineered by the Ascians to eventually be suitable host bodies for the Ancients upon the revival of their souls, though that's quite a stretch on my part.
There's a lot to answer and speculate on regarding Garleans, because they're shown to have wildly fantastic technology, swords capable of summoning tigers/performing aetherial geometry, dreadnaughts capable of killing primals, and basically anything the plot needs them to do. Most recently with the Ruby Weapon they did something really crazy, and the hint at how they did it means they've gotten a big tech boost from the spaceship that is The Ragnarok.
Of course, it's easy to say they were wiped away in The Flood of Light, but we can't tie that to a geographical location on The Source, because where races are/were differs shard to shard. Like how so many Au Ra are in Norvrandt. How the Lalafell are in what I'd consider Vylbrand(Kholusia). I think I could speculate about Garleans all day. :)