Another category of rabbinical interpretative literature dating back to this time is the Midrash. This goes back as far as 400BC, and we have copies dating to shortly before the time of Christ.
By the way, our Western legal tradition is very much derived from this. The rabbis believed that every word was inspired of God and no part of it was superfluous!
When you compare Midrash quotes of Scripture with the documents that serve as the basis for Bible translations today, they are virtually identical!