 The Cult of Skaro escaped the end of the Time War in a void ship along with a captured Time Lord prison ship containing millions of Daleks, which they call the Genesis Ark.In the episode "Doomsday", it is explained that the Genesis Ark can only be opened by the touch of a time-traveller and The Doctor and Rose Tyler both refuse, but Mickey Smith accidentally touches it, releasing the Daleks.The Doctor ultimately manages to use the vortex manipulator at the Torchwood Institute to suck what he believes to be all the Daleks back into the Void.