zaxarn

During the ages, the ZAXARN were steadily reducing their presence in the human space. They were concentrating all their assets into less and less systems, until they only occupied three of them, located in the Ka'Dis Sector: Nalil, Yito and Z3.

Everything they left behind was stripped of natural resources, exploited to the limit. We now call these Dead Worlds the ZAXARN Excavations. 

And where the Final Corporate War broke out and ZAXARN systems were attacked, the invaders have found out that there's nothing there.

We cannot even imagine what technology was required to totally dismantle entire planets - but they were gone. No celestial bodies other than stars, surrounded by dust clouds and sparse asteroid fields.
Of course, there's a chance that the planets were destroyed by some kind of weapon - but this prospect is even more terrifying. 

ZAXARN have disappeared completely.

 

Almost one thousand years later, the tttttnrh arrived. And they are masked (probably not like this, though). And ZAXARN were making masks. The most advanced masks ever.