1. There was a highly sophisticated civilization that appeared at least 15,000 years ago and is now lost to history.
2. This civilization was destroyed, almost without trace, in a catastrophe at the end of the last Ice Age.
3. Its elite survivors were able navigators who spread across the globe bringing the spark of civilization to benighted primitive populations.
4. The evidence for the existence of this Lost Civilization is indirect and circumstantial, such as inexplicable cultural similarities between supposedly separate ancient civilizations (such as pyramids on both sides of the Atlantic or a fascination with the stars) or the mysterious achievements of some ancient cultures (for example, the Nazca lines in Peru or the statues on Easter Island).
5. More familiar ancient cultures are alleged to allude to the arrival of these elite "Atlantean" visitors in legends and art (such as the Olmec Heads in Mexico, widespread myths about the flood, or tales of civilizing gods arriving from across the sea).