Tune in to Alien Invasion Week on History starting Monday 9/30 through Friday 10/4 for new Ancient Aliens, plus the premiere of In Search Of, new UFO Specials and More! Ancient Astronaut Theorists believe they have the answer the mysterious disappearance of the Mayan civilization in this clip from Season 9, "The Vanishings". #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 episodes on our site: http://po.st/AncientAliens Check out exclusive HISTORY content: History Newsletter: http://po.st/HistoryNewsletter Website - http://po.st/HistoryWeb Facebook - http://po.st/HistoryFacebook Twitter - http://po.st/HistoryTwitter "Ancient Aliens" explores the controversial theory that extraterrestrials have visited Earth for millions of years. HISTORY® is the leading destination for award-winning original series and specials that connect viewers with history in an informative, immersive, and entertaining manner across all platforms. The network’s all-original programming slate features a roster of hit series, premium documentaries, and scripted event programming.