After Alexander the Great unified the Eastern Mediterranean and Persia people could travel freely between those lands divided after his death. The Septuagint created converts to Judaism who spoke Greek as a primary language. Eventually 10% of the Roman Empire were Jewish. At this point Judaism became a religion as opposed to a race. Israelites under their own kings were often led astray by idolatry and sexual immorality (Isaiah 65:1 to 7) that the prophets tried to stop. The peak of Judaism happened while Israel was under foreign rule. Christianity weakened Judaism enough to tempt the Romans to firmly control it in 70 AD.
Police disperse hundreds in brawl in Kafr Manda, northern Israel (Haaretz)
from the article: A.B. Yehoshua: Americans, unlike Israelis, are only partial Jews