In the first century C.E., Judaism was marked by numerous sects and groups: Pharisees, Sadducees, Essenes, the Jews of Qumran, Zealots, Sicarii, “the Fourth Philosophy,” Christians, Samaritans, Therapeutae, and others. Judaism after 70 C.E., in contrast, was not marked by sectarianism. Samaritans persisted as a marginal group in Jewish society (even if they were numerous and active in their own right); Christians became predominantly gentile and, ultimately, a separate religion; but all the other groups virtually disappeared from the historical record, except for occasional rabbinic and patristic references to the second temple period. In their stead, the rabbis emerged as virtually the only group about which any information is extant. How can these facts be explained? There are two basic possibilities: either the shift in the nature of the available evidence gives the erroneous impression that sectarianism ceased, or the cessation of sectarianism was somehow caused by the war of 66-70 and the destruction of the temple. Scholars agree that the latter is far more likely than the former, but the subject is complex and both possibilities require discussion.
Shaye J.D. Cohen, From the Maccabees to the Mishnah (Philadelphia: The Westminster Press, 1987), 224.