The ruins of two large cities--Mohenjo-Daro and Harappa--tell much about the ancient civilization that arose in the valley of the Indus River. The two cities probably had more than 35,000 inhabitants each by about 2500 B.C. They also had brick buildings and well-planned streets laid out in rectangular patterns. The remains of hundreds of small settlements have also been found in the valley.<NP> The people of the Indus Valley had a well-developed system of agriculture that provided food for the area's large population. They dug ditches and canals to irrigate their farms. The Indus settlements traded with one another and with foreign cultures.
