Winter squash, maize aka corn, and beans.
Answer:
In order to stop the flow of silver out of Britain to pay for Chinese tea; Indian opium (Papaver Somniferum) grown in Bengal under the control of the British East India Company, was sold illegally through of a series of middlemen to the Cantonese Cohongs (Chinese trading companies).
Explanation:
We know this thanks to archaeologists who excavated many places and discovered that many early civilizations gathered around large rivers where they could develop agriculture. This was seen in places such as Mesopotamia, India, China, Egypt, etc.