From the Jerusalem Post: Lack of 2nd Temple period rabbinic control may have caused assimilation.

A deep linguistic and cultural chasm between the Jewish communities of the West and their brethren in the East led to the almost total assimilation of Western Greek and Latin-speaking Jews during the last centuries of the Roman Empire, according to a study by Prof. Doron Mendels of the Hebrew University and Dr. Arye Edrei of Tel Aviv University published in the January issue of The Journal for the Study of the Pseudepigrapha.

"We have quite decisively shown that the view that the rabbis [of the Talmud] had authority over the whole Jewish Diaspora in the Hellenistic period and later is not true," Mendels, an expert on the Hellenistic world and its Jews, told The Jerusalem Post on Monday.

"As of 70 [CE, the year of the destruction of the Second Temple,] onwards, when the rabbis become prominent as the leaders of the Jewish people, we claim that though they were leaders in the East, from Palestine to Babylonia, in the West, they never had any authority," Mendels said. [continue]