The Poretta system consists of five worlds, three of which are inhabitable by humans and have mineral-rich mountain ranges. The system was discovered by Adeptus Mechanicus Explorators in 365.M40, who found that it had already been colonised by the Demiurg. The Explorators tried to drive off the Demiurg with their own force of 5000 Tech Guard, but had to call in reinforcements in the form of two Valhallan Polar Guard regiments after suffering heavy casualties assaulting the Demiurg mountain stronghold on Poretta IV. The Valhallans captured the stronghold and forced the Demiurg to abandon Poretta. They were then given the honour of founding the first Imperial settlements in the system.