The second urbanization in India took place in about sixth century BC. The second urbanization in India centered the Ganga valley. Several factors account for the growth of urban centers or towns in the Ganga Valley in the sixth century BC.
First, of all improved knowledge of cultivation and the use of improved implements led to the production of surplus crops which were essential for the growth of towns. Second, particularly the use of iron became extensive. It was now possible to clear the deep forests with the help of iron implements that increased the area of cultivation.
Third; the emergence of business communities like the settees, gahapatis, sarthavahas, etc. was also an important factor behind the growth of towns in the Ganga Valley. Fourth, growth of trade and commerce in the sixth century BC was another important cause for the growth of towns.
Fifth, growth of towns was also associated with the large scale use of coin which was so essential for trade and commerce. These are in short the causes that led to the growth of urban centers in the Ganga Valley.