You can put the latest possible date on the translating as 130-ish CE, but that still means its prophecies, which came true, are nearly 2,000 years in coming to pass!
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Seventy-two Jewish scholars were asked by the Greek King of Egypt
Ptolemy II Philadelphus to translate the
Torah from
Biblical Hebrew into Greek, for inclusion in the
Library of Alexandria.
[11]
This is found in the
pseudepigraphic Letter of Aristeas to his brother Philocrates,
[12] and is repeated by
Philo of Alexandria,
Josephus[13][14] and by various later sources, including
St. Augustine.
[15] The story is also found in the Tractate
Megillah of the
Babylonian Talmud:
King Ptolemy once gathered 72 Elders. He placed them in 72 chambers, each of them in a separate one, without revealing to them why they were summoned. He entered each one's room and said: "Write for me the
Torah of
Moshe, your teacher". God put it in the heart of each one to translate identically as all the others did.
[5]
Philo of Alexandria, who relied extensively on the Septuagint,
[16] says that the number of scholars was chosen by selecting six scholars from each of the
twelve tribes of Israel.
The date of the 3rd century BCE is supported (for the Torah translation) by a number of factors, including the Greek being representative of early Koine, citations beginning as early as the 2nd century BCE, and early manuscripts datable to the 2nd century.
Source: Wikipedia