Onuru Sigma is a planet which once held a colony for another sapient, likely-spacefaring species - perhaps the Xel'Naga. Only one of this species' ancient cities is known to still exist, and it now lies in ruins. It is currently under the control of the Kel-Morian Combine, as it has been since the Guild Wars - it was likely taken during the Battle for Noranda Glacier, known as the first battle of the Guild Wars.