Nobody knows, there is no lore added for them on Uesp yet, and I can't remember finding any lore books about them.
Seems they were added without any attempt at explaining them.
RaddlemanNumber7 wrote: »A few sketchy lines of lore. Some more generic, kill-on-sight mobs. [snip]
I kind of wish they hadn't bothered.
[edited for minor bashing]
Fauns, meanwhile, are local to the Systres. They fill an ecological niche similar to Goblins back on mainland Tamriel and are about as charming and welcoming as those famously murderous and ill-tempered beings. Just why the Fauns reject other cultures with such violence is hard to say. But just as study into Goblin culture has been in fits and starts because of a propensity for the subjects to kill the researchers, an understanding of Faun dialect and tradition is sadly lacking.
RaddlemanNumber7 wrote: »A few sketchy lines of lore. Some more generic, kill-on-sight mobs. [snip]
I kind of wish they hadn't bothered.
[edited for minor bashing]