The Twelve Colonies were established by tribes who left their homeworld, Kobol, the alleged birthplace of humanity. There were at one time thirteen tribes, but one that was separated from the others instead went to a planet called Earth. In the 1978 series the thirteenth tribe were humans, but in the reimagined series the thirteenth tribe were presumed to be humans at first but eventually revealed to be humanoid Cylons. The humans of the Twelve Colonies (around 28.5 billion according to the official map released[1]) were virtually exterminated by the Cylons on the onset of both series, called the Second Cylon War. Only about 50,000 survivors managed to escape in a small collection of civilian spacecraft that survived the Cylon invasion, guarded by the Battlestar Galactica. The concept of twelve colonies alludes to the Twelve Tribes of Israel.