This ancient, populous and wealthy sector of the Segmentum Solar exists under constant threat from twin warp anomalies known as the Hellgates. In addition to periodic invasions from the Daemon worlds within the Gates, known as Hell Crusades, the planets of the Sector are tormented by Chaos cults and Heresies. Occident Prime's location within the Segmentum Solar less then a thousand light years from Holy Terra herself makes it a critical theatre in the Imperium's never ending war against Chaos.