Forbidden World

A Forbidden World, also called a Quarantined World, are planets that have been declared off-limits to contact with Imperial citizens by the government of the Imperium of Man, usually by the express order of the Inquisition. The existence of Forbidden Worlds is rarely made obvious to Imperial citizens but there are many of them throughout Imperial space. Travel to these worlds is forbidden except for the most well-informed and heavily armed expeditions, and even then only with a very good reason. Death Worlds, alien empires or planets where the creatures of the Warp have broken through into realspace are all examples of Quarantined Worlds, as are planets wracked with plague. Some worlds are quarantined because no one can fathom the origins of what has been found there, be it mysterious artefacts or ancient alien cities -- it is thought better to live in ignorance of what lies on such worlds than risk it becoming a threat. Other worlds are quarantined because every Imperial expeditionary mission there has failed to return. Planets are often quarantined by the pronouncements of the Inquisition, especially if they have uncovered some Warp taint or xenos infestation that cannot be cleansed. Many Forbidden Worlds possess great resources that would be extremely valuable to the Imperium if they were properly explored and exploited, but there are enough tales of ancient horrors awoken on sinister alien worlds that few Adepts would try to defy a planetary quarantine, particularly one backed by an Inquisitorial warrant.