Troy was fiction until someone found it. An "advanced" civilization 10,000 years ago wouldn't need to be all that advanced to seem amazing to others at that time. If they had farming with human built canals, some type of sewers, and skyscrapers as high as three stories they'd seem as advanced compared to others of that time as flying cars and interstellar travel seem to us today.
I suspect there's a lot of history older than 5,000 years old that is lost (probably forever) due to rising sea levels from melting ice sheets. Maybe Atlantis is part of that. Without writing the story would be corrupted a lot over the centuries as it is retold over and over again.