That would be the dead sea scrolls which is the oldest complete copy written in Hebrew and date to about 100BC. Although written by some heretics who only believed in the written law, it is 99% identical to the Massoraic version of the Torah. Josephous writes a summary of the Bible as well over a hundred and fifty years later but it is simply a summary written in Greek. The Nash Papyrus is from about 150 B.C.E. and contains a prayer listing the ten commandments in Hebrew which was read at that time before saying the Shema
http://en.wikipedia.org/wiki/Nash_Papyrus. That is the oldest Hebrew writing containing portions of the Bible.
The Aleppo codex used to contain the whole Torah before the muslims rioted and lost a good portion of it and it was copied directly from Masoraic manuscripts (meaning Orthodox Torah Jews) dating to the 1000 century B.C.E. based on widely confirmed historical writings about it but the manuscript itself is from the year 1000 or so. The original manuscript in the 1000 century B.C.E. that it was copied from have probably long turned into dust after such a long time.
According to Judaism, the first temple had on display the original Torah that Moses himself wrote so that Jews would go there and use it to copy other scrolls from as to make a genuine copy of the Torah. What happened to this scroll after the destruction of the first temple is unknown, but the scroll was most likely hidden under the temple with the ark.