In the case of the Jewish population, Israel is relatively close, with a comparatively higher standard of living and free entry, and there is a strong incentive for Jews to emigrate there even in the absence of hostility or outside pressure.
It’s not close - Israel is an island, you can’t drive or fly from Iran to Israel … yet
The Iranian Jews had to immigrate via another countries, I guess via Europe. Also boys had first to serve in the army to earn right to travel outside Iranian borders
