I've had this weird theory that generally, the more sophisticated the record keeping technology, the less the shelf-life. If I was to do this writing in clay tablets for instance versus paper versus the fragile digital tech we have now.
If this is true, then the corollary is that given say, some ancient civilization of say 3,500 years ago - perhaps the more sophisticated ones used record keeping technology that would become total dust a mere 2,000 year ago - while the less sophisticated ones have records which have survived.
Text on paper is much more redundant medium, and has much smaller information density.