During the rule of the Abbasids, the following changes occurred:
- Persian traditions strongly affected the caliphate.
- Non-Arab Muslims were allowed to hold powerful positions.
The other options listed either do not apply or are incorrect regarding the changes during the Abbasid period. For instance, Constantinople was never the capital of the Abbasid Caliphate; the capital was Baghdad. Additionally, the statement about Arab Muslims destroying Kairouan and rebuilding Carthage is not a significant event associated with the Abbasid rule.