Conversation so far:
what is the main source of income for India
India is an agriculture based country, where more than 50% of population depend on agriculture. This structures the main source of income.
What is India's main agricultural production
Today, India is a leading producer of lemons, oilseeds, bananas, mangoes and papayas, and the second-largest producer of wheat, rice, sugar cane, many vegetables, tea, cotton, and silkworms
What other sources of income does India have
India, with high population of low-cost, skilled, English-speaking, educated people, contributes to India's service industry, IT and business services outsourcing, a huge contributor to India's economical growth.

Question: What was the countrie's main source of trade in the past
Self-contained rewrite: What was India's main source of trade in the past