The history of the Jews in Europe spans a period of over two thousand years. Some Jews, a Judaean tribe from the Levant, migrated to Europe just before the rise of the Roman Empire (27 BCE). Although Alexandrian Jews had already migrated to Rome, a notable early event in the history of the Jews in the Roman Empire was the 63 BCE siege of Jerusalem.
The pre-World War II Jewish population of Europe is estimated to have been close to 9 million, or 57% of the world's Jewish population. Around 6 million Jews were killed in the Holocaust, which was followed by the emigration of much of the surviving population.
The Jewish population of Europe in 2010 was estimated to be approximately 1.4 million (0.2% of the European population), or 10% of the world's Jewish population. In the 21st century, France has the largest Jewish population in Europe, followed by the United Kingdom, Germany, Russia and Ukraine.
Hellenistic Judaism, originating from Alexandria, was present throughout the Roman Empire even before the Jewish–Roman wars. Large numbers of Jews lived in Greece (including the Greek isles in the Aegean and Crete) as early as the beginning of the 3rd century BCE. The first recorded mention of Judaism in Greece dates from 300 to 250 BCE, on the island of Rhodes. In the wake of Alexander the Great's conquests, Jews migrated from the Middle East to Greek settlements in the Eastern Mediterranean, spurred on by the opportunities they expected. As early as the middle of the 2nd century BCE, the Jewish author of the third book of the Oracula Sibyllina, addressing the "chosen people", says: "Every land is full of thee and every sea." The most diverse witnesses, such as Strabo, Philo, Seneca, Cicero, and Josephus, all mention Jewish populations in the cities of the Mediterranean Basin. Most Jewish population centers of this period were, however, still in the East (Judea and Syria) and Alexandria in Egypt was by far the most important of the Jewish communities, with the Jews in Philo's time inhabiting two of the five sections of the city.