Barbarus System

The Barbarus System is the lost home star system of the Death Guard, located in Segmentum Tempestus and the place where Mortarion was raised. Poisonous fog covers much of the system, and its terrain divides between the mountain strongholds of the Overlords and the valley farmland below. The XIV Legion, the Death Guard, later recruited from the same toxic slopes that had raised its primarch.

Humans could live only in the valleys. The high keeps belonged to xenos warlords until the ascent was completed, first by Mortarion and then by the Emperor. After the Horus Heresy, the loyalists left no usable recruiting world behind them. Later maps carry Barbarus only as a dead name: a feral-world system, meaning one whose human population had reverted to a primitive condition, that was scoured rather than garrisoned.

The Barbarus System remains relevant to Heresy-era records because the culture of the Death Guard formed there, not on a later plague planet. Unofficial summaries treat the system as Mortarion’s place of origin rather than as a living fortress of the forty-first millennium.