History and Genetics: Western Diaspora
The Western Diaspora, by which we refer primarily to the Mediterranean basin, was established during the Greco-Roman period. Beginning already soon after the conquest of Alexander the great in 323 BCE, Jews began to move to Egypt and to spread themselves further towards North Africa. Although Judah the Maccabee already sent ambassadors to Rome, it seems that the actual Jewish population originated somewhat later, probably in the aftermath of the destruction of the Second Temple in 70 CE, during the Great Revolt of 66-73 CE. In the centuries following, some fourteen synagogues were known to have existed in Rome and the populace and successful nature of the Jewish community, as well as their loyalty to Judaism, can be observed in the Jewish catacombs of Rome for the period of the second-fifth centuries CE. Jews had initially entered Italy through the boot, at Brundisium, coming from the Land of Israel. For this reason, Jewish communities existed along the entire length of Italy and constitute the origins of the Italian (“Italki”) part of the Jewish community of today’s Italy. The remaining Jews in Italy today are primarily Libyan, a group to which will return shortly.
The Roman Jewish community shows a low frequency of disease mutations that are found in Ashkenazic and Sephardic populations. This seems to confirm the historical claim that they were a progenitor of the Ashkenazic population and confirm the well-known fact that Spanish Portuguese Jews immigrated to Italy after the Expulsion from Spain in 1492 and intermarried with them.
During the Hellenistic period, as Jews spread westward along the southern shore of the Mediterranean, the Jewish communities of North Africa were established. Later on, large-scale migrations after the Expulsion from Spain in 1492 brought many Sephardic Jews to North African communities. However, Libya remained a rather isolated community. A particular mutation seems to date the founding of their community back about 23 generations ago. This is sometime around the colonization of North Africa by Jews during the Second Temple period, in the aftermath of the great revolt against Rome and 66 to 73 CE. Very few Jews settled in Libya after the initial immigration in antiquity. In fact, the Libyan Jews have been found to be essentially a genetic isolate. Interbreeding with the native population is been very minimal. This was an especially large Jewish community in antiquity and Josephus noted a large Jewish population of 500,000 in Cyrenaica, in present-day Libya. This community came to its and after the 1967 Six Day War and many Libyan Jews immigrated to Rome.