Why were Jews scattered throughout the known world in the Book of Acts?
The Jews were scattered because many taken into the Babylonian captivity never returned to the land of Israel. Instead they migrated into various regions of the then-known world, remaining there for several hundred years. By the Book of Acts, this dispersion had placed Jews and synagogues throughout Asia Minor, Greece, and Rome, wherever Paul traveled.
Les explains that when Paul began his missionary journeys through Asia Minor, Greece, and finally Rome, he consistently found Jews and synagogues already present. These Jews had been out in those areas for several hundred years because the Jews of the Babylonian captivity never chose to go back to the land of Israel; instead, they migrated into all the other areas of the then-known world. Les ties this to Nebuchadnezzar taking them captive in 606 B.C., which Jesus spoke of as the beginning of the times of the Gentiles. From that point, Jerusalem and the land of Israel were largely under Gentile powers, and that history helps explain why Jews were dispersed throughout the known world in the Book of Acts.