Ancient Jewish History: The Great Assembly
According to traditional Jewish historiography, the Great Assembly (Anshe Knesset HaGedolah) 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 two 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 Esreh, the standing prayer (Amidah) of 18, later 19, prayers that are still recited by Jews today. They canonized the Tanakh. Most important, 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 810 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.
Sources: Shamash