The series is set in the years 2119–2121 AD, several decades after humanity ("Terrans") has expanded its presence beyond Earth, terraforming and colonizing Venus and Mars. These three planets are "the Homeworlds", the core first of the Terran interplanetary state and later of Neosapien Commonwealth. Not all Terrans are affiliated with the Homeworlds, however: the Pirate Clans, descendants of Terran criminals exiled to the Outer Planets who live off looted Homeworlds' space freighters, are a major independent faction in the show. The first episode opens with the Earth Congress dispatching the entire Exofleet, humanity's space-based military, to counter the Pirate threat.