Limbo was a place outside of time historically ruled by Immortus. Limbo was a sort of "pocket universe", whose physical and temporal scope were extremely limited compared to the universe that ordinary human beings inhabited. To those within Limbo, it appeared roughly analogous to a planet, with a solid surface at one earth gravity and a sky devoid of stars. Instead of killing his foes, Rom banished Dire Wraiths to Limbo. Kang's city-base of Chronopolis was depicted as existing outside of time, and therefore could have been in temporal Limbo.