The academies were founded in pre-Islamic Babylonia under the Zoroastrian Sassanid dynasty .
The academies were were located not far from the Sassanid capital of Ctesiphon , which at that time was the largest city in the world .
The academies were founded in pre-Islamic Babylonia under the Zoroastrian Sassanid dynasty and were located not far from the Sassanid capital of Ctesiphon , which at that time was the largest city in the world .