In ancient times, the stories of God were passed down through generations by word of mouth. This is known as the “oral tradition.” It is not known who first recorded these stories, but some people estimate it could have been as early as 1,400 B.C. It is quite likely that Moses wrote down significant parts of the Torah: Exodus, Leviticus, Numbers, and Deuteronomy (Deuteronomy 31:9), although there is no scholarly consensus on how much or which parts he wrote.
The recording of all the books in the Old Testament did not happen at the same time. The process took centuries, and while some were being recorded, others were still being passed down orally. Once they were all written down, the process of collecting them all together probably began around 400 B.C.
All but a few sections of the Old Testament were originally written in Hebrew with parts of Daniel (chapters 2 – 7) and Ezra (chapters 4:8 – 6:18) written in Aramaic. After Alexander the Great swept through the Middle East in the fourth century B.C., Greek became the common language.
Not long after this, an Egyptian king asked the High Priest in Jerusalem for seventy scholars to translate the Jewish scriptures into Greek. This first translation became known as the Septuagint (meaning “seventy”). Sometime after the Romans destroyed Jerusalem in A.D. 70, a Jewish council discussed which books made up their Bible, what Christians now call the Old Testament. The rabbis recognized only the Hebrew / Aramaic canon, even though the Septuagint included other books.