The Kaloran System is the most far flung in the Helix Cluster, a harsh frontier in a frontier subsector. This far out, humanity strives to merely survive in an uncaring universe, wars and rumors of wars are a distant thing, as is the hand of the Imperium, yet to reach this far into the darkness. Kaloran would have little significance to the Sub-Sector and the Imperiums initial push into the area if it wasn’t for the megatons of food supplies it would be capable of producing. A single bulk freighter from Oligos would supply an army for months. And it is this basic resource that made it an early target for expansion when Castus Tharr established his foot hold in Corabie.
The Imperium, though, isn't the only force looking to the Kaloran System; vast Ork hordes, on the move after being displaced by the Great Crusade Coreward have begun an invasion of the system, quickly overrunning Kaloran and look to have the System firmly in control.