Where did the scattered Jews establish businesses and synagogues?
Wherever there was a city of any population of note, they established businesses and synagogues, spreading throughout every corner of the then-known world and across the whole Roman Empire. This migration began after the Babylonian exile, as Jews remained in the Gentile world rather than returning to Jerusalem.
Les teaches that the Jews became comfortable in the Gentile world and astute at banking and business. After being taken to Babylon, they did not all return to Jerusalem; instead they migrated to every corner of the then-known world. Wherever a city had any population of note, they established businesses and synagogues throughout the whole Roman Empire. This historical scattering explains why Acts 2:5 describes Jews from every nation under heaven dwelling at Jerusalem for Pentecost—devout men, keepers of the Law, and temple worshipers.