Did you know that some of the cities of the Indus Valley had between 35000 and 40000 people living in them? A vast number of settlements were built on the banks of the Indus River and surrounding areas. These settlements cover a remarkable region, almost 1.3 million square kilometres of land. The most important cities were Harappa, Mohenjo-Daro, Chanhudaro, Kalibangan, Banawali, Lothal, Dholavira, Sutkagendor, and Surkotada.
These cities were well planned, and solidly built of brick and stone. They had drainage systems, water storage systems, as well as systems for weights and trade. The people were craftsmen, traders, soldiers, and administrators. The city people got their grain and food from the villages. When the villages became too big, they needed a strong administration. They also began to produce excess grain, so that the people could devote themselves to other activities besides farming. This led to the growth of city civilizations.