Why is it that the number nine appears across the globe throughout history? Discover the origins of the group referred to as "The Mysterious Nine" in this preview. #AncientAliens Subscribe for more from Ancient Aliens and other great HISTORY shows: http://histv.co/SubscribeHistoryYT Find out ...

Is there a hidden city in the skies? Find out what the Chinese government could be hiding in this preview to "The Hidden Empire." #AncientAliens Subscribe for more from Ancient Aliens and other great HISTORY shows: http://histv.co/SubscribeHistoryYT Find out more about the show and watch full ...