And to add on; What were some of the ways in which trade and religion contributed to the increasing interaction between India and other proximate regions such as east Africa, Arabia and east Asia?
I know a little about this because I wrote my senior thesis on the Silk Road during the first few centuries CE.
In the case of Buddhism, trade spread the religion eastward, and trade routes enabled Chinese pilgrims like Xuanzang to travel back to India to retrieve Buddhist texts. The region I studied, the Gandhara region under the Kushan dynasty, saw a vast increase of wealth because of Silk Road routes that went through the region. This wealth went into the sangha and created a major flowering of Buddhist art and literature. I suspect that the newfound wealth of the Buddhist sangha, and its expanded role for the lay donors who enabled that wealth, laid the groundwork for the later development of Mahayana Buddhism. This new wealth also made Buddhism a more socially acceptable religion.
If you're curious about Silk Road stuff, one good book on this is Xinru Liu's Ancient India and Ancient China: Trade and Religious Exchanges, AD 1-600. It's out of print and hard to find on Amazon, but I have a PDF if you want it.