The next version of the Old Testament that we are going to discuss is the Septuagint. During the Greek empire Greek became an international standard language. Many of the Jews were able to return to Jerusalem. However there will still Jews in other parts of the Empire including Alexandria, Egypt and Athens, Greece, etc. Many of these Jews no longer spoke or read Hebrew, and there was a push to have all reading, writing, and worship in Greek.
As a result, a group of Jewish scholars translated the Hebrew scrolls into Greek. The Bible that resulted included Jewish histories, including the Books of the Macabees, and various Jewish prophets that lived during the Babylonian, Persian, and Greek periods. Many of these were never written in Hebrew.
The Septuagint was the Bible which Christ and his disciples used. No doubt they also read and were familiar with many other texts.
Now I do not wish to give my readers a false impression that the Septuagint is therefore truer or better than other versions. Like all bibles, the Septuagint was compiled from various libraries which may not have had all the religious texts, and many texts would be included or excluded based upon whatever criteria the scholars thought was best. Their views may have been affected by politics, tradition, the biases they had, as well as a effort to justify their own actions and the actions of others.
Also the Septuagint has allegedly become corrupted over time. Retranslations, omissions, and alterations have changed much of the meaning of certain passages and doctrines. Comparison with the Dead Sea Scrolls shows that it is still fairly close, but confirms that changes have been made.
Nevertheless, the Septuagint contains many good faith promoting stories and events. The books and portions of books it contains that are absent from the Hebrew Bible are:
Tobias
Judith
Wisdom (of Solomon)
Ecclesiasticus
1st Macabees
2nd Macabees
Baruch 1-5
Baruch 6
Esther 10:4-16:24
Daniel 3:24-90
Daniel 13 & 14
1st Esdras
2nd Esdras
Prayer of Mannasseh
The main reason why the Septuagint ought to be taken seriously by practicing Chtistians and Jews is that we know that Jesus Christ (Yeshua) was very familiar with it because he quotes from it. This fact tells us two very important things. Firstly Christ would not have quoted from a text He had not read and studied and Himself believed to be fundamentally true. Secondly He would not have quoted from it unless it was widely accepted among the Jews that He was teaching. At the time of Christ, the Septuagint was the Bible.
When the early Roman Christian church was forming under Constantine, at the Counsil of Nicea (AD 325) the basic Christian doctrine was decided upon and the Nicean Creed was issued, and at a later Cousil of Carthage (AD 393, 397), the books that made up the New Testament as we know it were solidified. However, for the Old Testament they kept what was already in the Bible at the time which was the Septuagint. So for centuries the Septuagint remained the standard Old Testament for most Christians.