rabbinical regulations ("de-rabbanan"). Historical development Source and transmission According to modern scholarship, the traditions embodied in what later became known as the "Oral Torah" developed over generations among the inhabitants of Judea and were passed down through various modes of cultural transmission, including but not restricted to oral transmission. It is hypothesized that, sometime prior to the Babylonian exile of 586-530 BCE, in applying the Mosaic code to daily life and Temple worship, "a multitude of usages arising out of practical necessity or convenience or experience became part of the routine of observance of the code, and, in the course of time, shared the sanctity and authority which were inherent in the divinely inspired code itself." Such practices experienced exponential growth from the time of Ezra to the Romans' destruction of the Second Temple due to the changing social and religious conditions experienced by inhabitants of Judea. Many of these practices were advocated by the Pharisees, a sect of largely lower- and middle-class Jews who stood in opposition to the Sadducees, the priestly caste who dominated the Temple cult. The Sadducees rejected the legitimacy of any extra-biblical law or tradition, as well as increasingly popular notions such as the immortality of the soul and divine intervention. Danby notes the following: It is a reasonable hypothesis that a result of this controversy—a controversy which continued for two centuries—was a deliberate compilation and justification of the unwritten tradition by the Pharisean party, perhaps unsystematic and on a small scale in the earlier stages, but stimulated and fostered from time to time both by opposition from the Sadducees and by internal controversy (such as, e.g., the disputes between the House of Hillel and Shammai) within the ranks of the Pharisees, culminating in the collections of traditional laws (Halakoth) from which the present Mishnah draws its material. With the destruction of the Second Temple around 70 CE, the Sadducees were divested of their main source of authority, without which their theology could not survive. On the other hand, the Pharisees became the progenitor of the rabbinic class, who formalized the traditions of their predecessors. Following the fall of the Temple, it appears that the Pharisaic leader Johanan ben Zakkai (30-90 CE) settled in Yavneh, where he established a school that came to be regarded by fellow Jews as the successors of the Jerusalem Sanhedrin. Upon this Council of Jabneh fell the duty of administering