In the fertile river valley along the border of modern-day India and Pakistan, the Indus Valley Civilization built some of the largest cities in the ancient world. Feeding such a large population would have been a significant challenge. New research from Kalyan Sekhar Chakraborty reveals one of the ways the civilization was able to sustain so many people. The postdoctoral researcher at the University of Toronto Mississauga has shown that dairy was being produced as far back as 2500 BCE. It is the earliest known dairy production in India, and could have helped produce the type of food surplus needed for trade.
source https://phys.org/news/2020-10-uncovers-evidence-earliest-dairy-production.html