Since the Pharisees lacked a central authority, prior to the destruction of the temple there was no fixed form or content to the oral instruction communicated by each rabbi. Yet, during the early 1st c. CE, two schools of interpretation became influential among Judean Pharisees: the school of Shammai & the school of Hillel. After the destruction of Jerusalem (70 CE), Johanan ben Zakkai, the last of Hillel's disciples established an Academy at the Judean seaport of Jabneh (Greek: Jamnia), with the aid of the remnants of the school of Hillel & some Shammaites. Since the former chief institutions of Judean religion, temple & Sanhedrin, were no longer in existence, this rabbinic Academy acted as the supreme authority for the regulation of Jewish life. Yet, recognition of its authority by other Jews was neither immediate nor universal prior to the end of the 1st c. CE.

The rabbinic Academy underwent a major crisis during the bar Kochba messianic uprising under Hadrian (135 CE), in which its president [Aqiba ben Joseph] & other leading rabbis were executed. In the aftermath Simeon II ben Gamaliel II [a descendent of Hillel] was prevailed upon to move the Academy from Judea to Usha in southwestern Galilee. His son Judah "the Prince" [ha Nasi] relocated it further inland, first at Beth Shearim & then (about 175 CE) at Sepphoris, the ancient capital of Galilee. Thus, from the middle of the 2nd c. CE, Galilee replaced Judea as the center for the development of rabbinic tradition. About 250 CE Johanan bar Nappa^cha moved the center of the Academy to Tiberias, on the southwestern shore of the Sea of Galilee.