You find some historical documents on a disk in a desert cave.
Is it a stone disk with markings, or a compact disk of files?
Which would you be more likely to trust as a reliable source?
The stone disk may be verifiably more ancient. But the CD could contain old data, accurately copied & pasted many times onto new formats, losing none of the original. Would you penalise a community who used advanced technology, presuming that because they did so, they hadn't kept an accurate record of their history?
That seems to be the question behind assumptions on the reliability of the Old Testament with regard to ancient records and manuscripts. Read Peter Williams' short & helpful theologynetwork article.