The final version of the Septuagint was published in 132 BC, and included the books of Proverbs, Ecclesiastes, Song of Songs, and Wisdom of Solomon within the Wisdom Section of the Septuagint, while the Psalms of Solomon were added as an appendix later, sometime in the 1st century BC. It appears to have been translated between 200 and 140 BC from Aramaic translations.
The book of Proverbs is generally attributed to King Solomon, who is explicitly referred to as the author of some of the proverbs. A number of proverbs are known to have been copied from older collections of proverbs, most notably the Wisdom of Amenemope, which was apparently written by Amenemope son of Kanakht sometime before Pharaoh Akhenaten, circa 1350 BC.
The book of Ecclesiastes is generally attributed to King Solomon, however, he is not mentioned anywhere by name. The current view of the academic community is to regard the text as a Persian or Greek era text, something that dates to long after the time of Solomon.
The Song of Songs appears to be love poetry, exchanged between Solomon and one of his wives, however, is not clear who exactly the wife was. The wife describes herself as black, suggesting a Kushite woman. She also refers to herself as a Shulammitess, and makes clear she was not from Jerusalem. The town of Shunaam was located near the Jezreel Valley north of Mount Gilboa, in the tribal lands of Issachar at the time. It was also listed as one of the towns conquered by the Egyptian Pharaoh Thutmose III circa 1450 BC, and then again by Pharaoh Shoshenk I circa 925 BC, meaning there was a significant town was there for over 500 years. It was the hometown of King David's last concubine, the 12-year-old Abishag, who Adonijah attempted to marry after David's death, which suggests the author was Abishag the Shulamite.
The Wisdom of Solomon was added to the Septuagint sometime between 250 and 132 BC, and while it was traditionally attributed to King Solomon, this book was never copied by the Masoretes, and no fragments of it have been found among the Dead Sea Scrolls, indicating it was not used much in Judea, if at all. A Syriac version of it is included in the Peshitta, the Syrian Orthodox Bible, which the Syrian Orthodox Church has always claimed was transcribed from the Aramaic text that the Jews translated into Hebrew, however, most modern scholars believe the Peshitta was a Syriac translation of the Septuagint.
Like the Wisdom of Solomon, the Psalms of Solomon were not copied by the Masoretes, and no fragments of it have been found among the Dead Sea Scrolls, indicating it was not used much in Judea, if at all. There is also a Syriac version of it in the Peshitta, which the Syrian Orthodox Church has always claimed was transcribed from an Aramaic copy, however, most modern scholars believe the Peshitta was a Syriac translation of the Septuagint.
The origin of the book is unclear and widely debated. The name Solomon is used in this translation, as it is the name used in the Codex Alexandrinus, however, it should be noted that about half the manuscripts use the name Salomôn (Σαλομών) or Salômôn (Σαλωμών) instead of Solomôn (Σολομῶν) or Solômôn (Σολωμών). This could be a transliteration error, however, the name Solomon must have been well known by the time these Psalms were translated into Greek, so the consistent use of the alternate spelling appears to be intentional. It is possible that the translators and scribes who used the alternate spelling did so in the belief that the author of these Psalms was named Salomon, as he certainly could not have been King Solomon.
