They didn't have the military power to defend themselves.
Answer:
eastern, Tigris and Euphrates
Mesopotamia lay at the eastern end of the Fertile Crescent, in the valley between the Tigris and Euphrates rivers.
Hinduism reinforced a strict social hierarchy called a caste system that made it nearly impossible for people to move outside of their social station. Emperors during the Gupta empire used Hinduism as a unifying religion and focused on Hinduism as a means for personal salvation.
