How did mountain passes influence the rise and decline of ancient Indian empires?

Mountain passes played a crucial role in the rise and decline of ancient Indian empires by facilitating trade, cultural exchange, and military movements. Strategic passes, like the Khyber Pass, allowed empires such as the Maurya and Gupta to expand their territories and influence by enabling access to neighboring regions. Conversely, these same passes also served as invasion routes for foreign powers, contributing to the decline of empires when they faced external threats. Thus, control over these passes was vital for maintaining power and stability in ancient India.