Talmud Originally, Jewish scholarship was oral. Rabbis expounded and debated the law (the written law expressed in the Hebrew Bible) and discussed the Tanakh without the benefit of written works (other than the biblical books themselves), though some may have made private notes (), for example of court decisions. This situation changed drastically, however, mainly as the result of the destruction of the Jewish commonwealth in the year 70 CE and the consequent upheaval of Jewish social and legal norms. As the rabbis were required to face a new reality—mainly Judaism without a Temple (to serve as the center of teaching and study) and Judea without autonomy—there was a flurry of legal discourse and the old system of oral scholarship could not be maintained. It is during this period that rabbinic discourse began to be recorded in writing. The earliest recorded oral law may have been of the midrashic form, in which halakhic discussion is structured as exegetical commentary on the Pentateuch (Torah). But an alternative form, organized by subject matter instead of by biblical verse, became dominant about the year 200 CE, when Rabbi Judah haNasi redacted the Mishnah (). The Oral Law was far from monolithic; rather, it varied among various schools. The most famous two were the School of Shammai and the School of Hillel. In general, all valid opinions, even the non-normative ones, were recorded in the Talmud. The Talmud has two components: the Mishnah (c. 200 CE), the first written compendium of Judaism's Oral Law; and the Gemara (c. 500 CE), a discussion of the Mishnah and related Tannaitic writings that often ventures onto other subjects and expounds broadly on the Tanakh. The rabbis of the Mishnah are known as Tannaim (sing. Tanna תנא). The rabbis of the Gemara are referred to as Amoraim (sing. Amora אמורא). Mishnah The Mishnah does not claim to be the development of new laws, but merely the collection of existing oral laws, traditions and traditional wisdom. The rabbis who contributed to the Mishnah are known as the Tannaim, of whom approximately 120 are known. The period during which the Mishnah was assembled spanned about 130 years, and five generations. Most of the Mishnah is related without attribution (). This usually indicates that many sages taught so, or that Judah haNasi who redacted the Mishnah together with his academy/court ruled so. The halakhic ruling usually follows that view. Sometimes, however,