History of Jewish Prayer
Regular communal Jewish prayer began as a substitute for the sacrificial cult in the ancient Temple in Jerusalem. The daily offerings there were accompanied, according to later rabbinic sources, by the recitation of biblical passages and extra-biblical liturgies. Some Psalms were perhaps sung in the Temple by choirs of Levites, who aided the priests with the temple service. Even in outlying districts there were prayer gatherings on various occasions. These were mere accoutrements, though; the focus of worship was on animal sacrifices.
The formative period of Jewish prayer was that of the Tannaim, the sages whose oral traditions of law and legend are gathered in the Mishnah (edited c. 200 C.E.) and some early collections of midrash. From their traditions, later committed to writing, we learn that the generation of rabbis active at the time of the destruction of the Second Temple (70 C.E.) gave Jewish prayer its structure and, in outline form at least, its contents.
Their liturgy consisted of three primary corpuses: (1) the twice-daily recitation of the Shema--the central statement of Jewish monotheistic belief--and the formulaic blessings (berakhot) recited before and after it; (2) "The Prayer" of 18 blessings, also known as the Amidah--recited several times daily, and (3) the public recitation of the Torah in installments.
To what extent were the Tannaim inventing the liturgical formulas and patterns they prescribed and to what extent were they standardizing and canonizing various local customs that preceded them? This question is still the subject of scholarly debate. So too, is the question of whether there was one fully elaborated "text" for all these prayers--of which later customs are variants--or whether the Tannaim established only themes and key phrases, without dictating a specific full wording for each mandatory blessing.