Rebecca,
With all due respect, if I am correct, most of the Jewish documents were continually being destroyed, burned and whatever means our oppressors had to get rid of them. As you may also know, most times we were even forbidden to pray or use our Holy Scriptures. Of course that doesn't say anything for "authenticity" of dated documents, but I thought I had to mention it. If not for the destruction of our scrolls, who knows how far back in history documentation would have been found.