Movement of goods, peoples & culture has been very old in Indian Ocean sub continents with the Indian Ocean playing the crucial role. There are many archeological and other proofs of these interactions. The interactions can be understood as within sub continents & with Inter subcontinent.
Interaction of Peoples with in Indian Subcontinent
During the Iron Age, two major highways connected the subcontinent. Uttra Path is the first one and is an east west road which ran from eastern Afghanistan, across the gangetic plains to ports of Bengal. Today this road is famous for national highway 1 between Amritsar & Delhi and as national highway 2 between Delhi & Kolkata. The second was Dakshina path and was a north south highway. It started around the Allahabad-Varanasi section of Gangetic plains and made its way to a south westerly direction to Ujjain. Here it splits into two with one branch going to ports of Gujarat & second branch making its way further south via Partisthana to Kishikanda in Karnataka & beyond. People’s cultures had moved along these highways. Many of events described in epics took place along them.
Also, Read Early Traders of the Indian Ocean Rim
Interaction Peoples along the Eastern Rim
The injection of Indian DNA into Australia around 2000 BC shows that people living on India’s eastern sea board were capable of sailing long distances even before the Iron Age. But trade boom had started around 800 BC with its hub at Kalinga & the adjoining areas of West Bengal. Many ancient ports have been found along the coast between the western most mouth of Ganga & Chilka Lake. With Chilka Lake working as a safe harbor. Initially, the Bengali- Odiya Mariners would have sailed along the coast & avoided across Indian Ocean path. They would have traded along Andhra, Tamil & up to Sri-Lanka. Genetic studies suggest that migrants from eastern India form the dominant population in Sri-Lanka. They named as Sinhalese.
Knowledge of Monsoon & Ocean Currents
By the end of second century BC, Indian Mariners appears to have learned enough about monsoon winds & ocean currents to attempt a more southern route across the Indian Ocean to the islands of Indonesia. The Mariners of Kalinga were using Chilka Lake as safe harbor and launch point. They might have used north eastern monsoon winds that blow from mid-November to sail down the coast of Sri-Lanka. After trading & taking fresh supplies they must have used ocean currents to cross the Indian Ocean to the northern tip of Sumatra. From here the ships could sail down straits of Malacca towards Borneo & Vietnam. Alternatively, they could have headed south towards Bali & Jawa. After finishing their purchases & sales most ships would have used the counter currents to return Srilanka & then Odisha.
If the sailors started from Odisha in Mid-November they might have reached Bali & Java by Mid-January. After trading for two months, they would have sailed back to Sri Lanka to catch south west monsoon winds in May that would take them home. These traders were not only from Odisha, they must have belonged to Andhra, Tamil & Bengal. Also, The trade might have been bi-directional.
Trade links with south east Asia led to cultural exchange. The era of maritime exploration & trade is still remembered in Odisha in folklore & festivals. Also, These festivals are according to the start & return time of sailors. Indic civilization had strong Impact on the region. Buddhist & Hindu religions, epics, Sanskrit language & scripts were interchanged & had an effect on the region. Still, Buddhism is a dominant religion across Myanmar to Vietnam, while Hinduism survives in pockets such as Bali.
What they Trade?
The most important Indian export was cotton textiles. Moreover, Indian imports were including Chinese silk via ports in Vietnam and the camphor from Sumatra. While Islands of Indonesia would have been a source of cloves, nutmeg & other species. But, Many of the species thought to be Indian by medieval Europeans. Actually, they were from Indonesia except for black pepper which grows along the south-western coast of India. There were many goods in trade whose origination or consumption destination was middle east. This means Indian subcontinent also used to act as a connection between Middle east & far South East Asia.
(The article is based on the book “The ocean of churn” by Sanjeev Sanyal.)