Historians use ancient scriptures, literature, coins, artifacts, and other things to learn about trade and trade routes. Historians generally use oral stories from people who lived in ancient times and evidence found in ruins at a site. They choose that information which they consider important and reliable which will serve as evidence. Every historian may analyze the same findings and draw a different result.

Literature such as Sangam poems or Sangam literature of that period.

• Buddha's presence was depicted in sculptures using certain symbols. For example, his knowledge was obtained using sculptures of a Peepal tree. It showed connections with different parts of the world.

• Objects like earthen pots, bowls and plates were found at many sites.

• Roman gold coins were found in some parts of South India which show the relationship between Rome and ancient India.