Illyrium is a region in the far north of Macragge (also called Illyria or simply "bandit country"). It was the last region of the planet conquered by the central government, resisting all attempts until Roboute Guilliman was dispatched by his foster-father and Consul Konor to pacify it with an expeditionary force.
It remained a haven for outcasts and criminals even after this pacification. During the Imperium Secundus period, Konrad Curze used it as a hideout and established a base of support there, resulting in its devastation by the Dark Angels Dreadwing. Even millennia later, during the Plague Wars, Illyrium was a haven of dissent and mutiny, with its Ultramar Auxilia repeatedly rebelling until the reborn primarch arrived and quelled them.
Illyria was a region in the western part of the Balkan Peninsula inhabited by numerous tribes of people collectively known as the Illyrians. It was conquered by the Romans in 168 BC in the aftermath of the Illyrian Wars.
- 1: Codex: Space Marines (5th Edition) pg. 12
- 2: Angels of Caliban (Novel)[Needs Citation]
- 3: Warhammer 40,000 8th Edition Rulebook pg. 154