The correct answer is - when crops such as millet were found along the banks.
The Indus Valley is a valley that has a very big river flowing through it, and also very fertile soil around its banks, but it wasn't until the discovering of the millet and its nutrition value that the valley has been used for farming. Once the people recognized the potential of the millet as a big and stable food source, they started to use the advantages of the fertile valley and develop the agriculture in this part of the world.
Explanation: This was an establishment that became popular gathering places in the eighteenth century in which the cities where full of merchants, captains, and traders and they discuss about new adventures and they keep up with the most recent events in those cities.
