Romans traded with India in considerable quantities during the Imperial period. We have several sources that confirm this information- Pliny, Strabo, the Periplus of the Erythraean Sea, as well as archeological evidence.

India has a tropical climate, which allows a variety of spices to grow that could not be grown in the empire. Products such as cinnamon, pepper, incense, and more were extremely popular in the Empire and could only be grown in India or, in some cases, the Arabian peninsula. Pliny explains that ‘the climate is unrelenting. The pepper-vine will live in Italy, the cassia-plant can grow in northern climates and incense-trees have been known to survive in Lydia. But we do not have the sunshine to ripen their fruit or make their resin productive.’

Trade occurred over the land route through the Parthian Empire, known as the Silk Road, and via the sea. Every year, over 120 Roman ships would sail east with the monsoon winds. They left from Egypt, sailed down the Red Sea, and across the Indian Ocean. According to the Periplus of the Erythraean Sea, there were major ports along the Horn of Africa, likely all the way down to modern Tanzania, in the Arabian peninsula, and along the western coast of India. Interestingly, it seems that the Roman merchants didn’t travel to the East coast of India and instead remained on the western shores.

The Romans imported far more products than they exported. This resulted in a considerable trade deficit, since the Romans had to pay for all imported products in gold and silver. However, international trade provided the Roman government with considerable revenues. Rome taxed all imported wares at a quarter rate and again at one fortieth rate when the products moved to a new province except Rome. Alexandria became the hub for eastern trade. Merchants would bring their wares through the great city before dispersing throughout the empire. This, along with the grain supply, was the reason that Egypt was so valuable to the Empire.

It was also possible for individual Romans to travel to India and vice versa. To provide an example- The Greek orator Dio Chrysostom mentions how Indian people could be seen at large gatherings at Alexandria, including the crowd that came to hear his speeches. He describes how ‘Ethiopians and Arabians from distant regions and Bactrians, Scythians, Persians and a few Indians all help to make up the audience in your theatre and sit beside you on each occasion’.

Militarily, the closest the Roman armies ever got to India occurred during Trajan’s eastern campaigns in Parthia. Trajan lead the legions to the Persian gulf and very likely would have kept going. However, he was forced to turn back west to quell numerous revolts and died shortly thereafter. His successor, Hadrian, deemed the new territories too expensive to maintain and stopped the eastern expansion.

Great Source: The Roman Empire and the Indian Sea by Raoul McLaughlin