Answer:
   
   According to traditional Jewish historiography, this was an assembly
   of 120 rabbis that ruled in the period after the time of the prophets
   up to the time of the development of rabbinic Judaism in 70 CE. They
   bridge a period of about 2 centuries. The tradition teaches that they
   redacted the books of Ezekiel, the twelve minor prophets (The Trei
   Asar), and the books of Daniel and Esther. They also composed the
   Shemonah Esrah, the standing prayer (Amidah) of 18, later 19, prayers
   that is still recited by Jews today. They canonized the Tanakh (Hebrew
   Bible). Most importantly, they enacted a democratization of Jewish
   education, making the Torah the possession of all, instead of just the
   priestly class.
   
   Historically, the Great Assembly described in Nehemiah 8-10 was a
   public assembly of Jews who returned to Israel after the exile in
   Babylonia. In this gathering the leaders and people of Israel
   rededicated themselves to the Torah as their inheritance and code of
   law.