Fairly Self explanetory name, they have Hidden both their forms and thier entire System(potential faction ablity) away from the rest of the Galaxy, Hidden from the Endless, the Dust Wars the Mezari etc. It is how they have survived so long without foriegn interference. 

*Non-name related stuff* There reason for being a force in the Galaxy only now could be their recent introduction to dust, a substance completely alien to them as a result of their self-imposed Isolation. via the Massive dust explosion caused by the Gray Owl.  Their recation to dust could be Positive(Lumeris, Vodyani) or Negative(Harmony) and would likey be a focal point of their faction quest.