There have been statements that during the period of Iran before the revolution in 1979, (period during Shah) the Iranian passport was very strong, meaning it could visit many places without a visa, such as European nations. Further, it was rumored travel to the US was easy.  This is stark in difference, as today their passport is very weak, and they need a visa for every European country, and US visas are difficult. Try to find one credible source that proves the passport was stronger during the period of Iran pre 1979.