Graham Hancock shouldn't need an introduction if you are interested in non-mainstream explanations for civilization before 4,000BC. He is the author of Fingerprints of the Gods, The Mystery of the Sphinx, and Magicians of the Gods - among other books. In this video he discusses evidence of civilization and of cataclysm approximately 12,000 years ago - from Gobekli Tepe to ancient source maps (including details of Antarctica) from a lost civilization like Atlantis from before the last pole shift, to comet impact to the end of the last ice age and mass extinctions...