Septuagint
The Septuagint (LXX) is the name commonly given in the West to the Koine Greek translation of the Jewish scriptures, translated in stages between the 3rd to 1st century BCE in Alexandria, Egypt.
According to Michael Barber, "In the Septuagint, the Torah and Nevi'im are established as canonical, but the Ketuvim appear not to have been definitively canonized yet (some editions of the Septuagint include, for instance I–IV Maccabees or the 151st Psalm, while others do not include them, also there are the Septuagint additions to Esther, Jeremiah, and Daniel and 1 Esdras). There is a popular legend that seventy (or seventy-two) elders translated the Hebrew Bible into Koine Greek but the historical evidence for this story is rather sketchy. Whoever the actual scribes may have been, it seems likely that the Torah was the first to be translated." Beyond that, according to Barber, it is virtually impossible to determine when each of the other various books was incorporated into the Septuagint.
The authority of the larger group of writings out of which the Kethuvim were selected had not yet been determined, although some sort of selective process must have been employed because the Septuagint did not include other well-known Jewish documents such as Enoch or Jubilees or other writings that are now part of the Pseudepigrapha. It is not known what principles were used to determine the contents of the Septuagint beyond the Law and the Prophets.
The Septuagint was held with great respect in ancient times; Philo and Josephus (both associated with first century Hellenistic Judaism) ascribed divine inspiration to its translators, and the primary ancient account of the process is the circa 2nd century BCE Letter of Aristeas. Some of the Dead Sea Scrolls attest to Hebrew texts other than those on which the Masoretic Text was based; in some cases, these newly found texts accord with the Septuagint version.
Read more about this topic: Development Of The Hebrew Bible Canon