What did Jews establish in notable cities throughout the Roman Empire?
In cities of notable population throughout the Roman Empire, Jews established businesses and synagogues, along with other community institutions. This pattern grew from their dispersion after the Babylonian captivity, as they migrated across the known world rather than returning wholesale to Jerusalem.
Les teaches that the Jews became comfortable in the Gentile world and astute at banking and business. After being taken out to Babylon, many did not return to Jerusalem but migrated to every corner of the then-known world. Wherever there was a city of any population of note, Jews established businesses and synagogues, and what have you, everywhere throughout the whole Roman Empire. Les explains that this historical background makes sense of Acts 2:5, where Jews from every nation under heaven were dwelling at Jerusalem for the Feast of Pentecost. They had scattered throughout the known world after the Babylonian deportation instead of going back to Jerusalem.