Nevertheless, Sir Thomas Arnold does acknowledge that the persecution of Zoroastrians did take place later on. Stepaniants states that many persecutions took place during the reign of the Abbasids, and around that time was when the Parsi exodus took place. But regardless, both Arnold and Stepaniants say that the Islam is not to blamed entirely for the decline of Zoroastrianism.
However, it is worth noting that Sir Thomas Arnold recognizes persecution of Zoroastrians took place later on, whereas Stepaniants suggests many persecutions occurred during the Abbasid reign, coinciding with the Parsi exodus. Nonetheless, both authors agree Islam is not entirely to blame for the decline of Zoroastrianism.