According to Jewish tradition the Great Assembly (Hebrew: כְּנֶסֶת הַגְּדוֹלָה, romanized: Kəneset haGədōlā, also translated as Great Synagogue or Synod) was an assembly of possibly 120 scribes, sages, and prophets, which existed from the early Second Temple period (around 516 BCE) to the early Hellenistic period (which began in the region with Alexander's conquest in 332 BCE), roughly coinciding with the Persian hegemony over the nation of Israel.
[2] Among the developments in Judaism that are attributed to the rabbis of this period are the fixing of the Jewish biblical canon (including the Book of Ezekiel, Daniel, Esther, and the Twelve Minor Prophets); the introduction of the Feast of Purim; and the institution of many prayers and rituals including the Amidah prayer.
These passages indicate that this assembly was believed to be the one described in Nehemiah 9–10, and other statements regarding it prove that the Amoraim accepted this identification as a matter of course.
[30] In view of these facts, it was natural that the Great Assembly should be regarded as the connecting-link in the chain of tradition between the Prophets and the sages.
[35] In addition to fixing the ritual observances for the first two quarters of the day,[36] the Great Assembly engaged in legislative proceedings, making laws as summarized in the Book of Nehemiah.
[37] Tradition therefore ascribed to it the character of a chief magistracy, and its members, or rather its leaders, including the prophets of that time, were regarded as the authors of other obligatory rules.
In traditional literature, however, a distinction was generally drawn between the institutions of Ezra and those of the men of the Great Assembly, so that they figured separately.
The following rulings were ascribed to the men of the Great Assembly: According to Sherira Gaon, the extensive traditions of the Oral Torah (first recorded in the Mishnah) were known by the Great Assembly, but transmitted orally from generation to generation, until eventually being recorded in the names of later sages.
[1] Louis Jacobs, while not endorsing this view, remarks that "references in the [later] Rabbinic literature to the Men of the Great Synagogue can be taken to mean that ideas, rules, and prayers, seen to be pre-Rabbinic but post-biblical, were often fathered upon them".