The Mauryan and Gupta is located in modern day India. India is a peninsula and a sub-continent isolated from the rest of Asia. India had terrains of mountains, foothills, plains, forests, and steppes. The India is dry and agriculture there relies on irrigation. While the Han Dynasty in China has more fertile land near river and had major irrigation systems such as dams to control flooding. It also is connected to the Silk Road which allows interaction with the Roman and Parthian Empires in order to exchange ideas while the Mauryan and Gupta Empires where isolated from this due to its geographical location.
The Qin who set up the foundation for Han Empire believed in legalism which was a strict code of law. Thus allowing a strong discipline military system. In contrast to that the Mauryan and Gupta Empire where Buddhist, Hindu, and Jainist who believed the in a non-violence way to approach things. Thus giving the Mauryan and Gupta empires a smaller number of people who could be legible for the military while the Qin could draft anyone giving them a larger army.
The Mauryan and Gupta had a caste system know as varna which divides people into social five categories. This caste system does allow the people to move up from their class because the people of the lower-class accepted this thinking that if they followed the rules of their class they will be reincarnated into higher class. Thus meaning keeping a large number of people where