What do the planned cities of the Indus River Valley tell us about the culture?

The fact that the Indus River Civilization, or Harappan society, was made by prolific city builders allows us to infer a number of things about its culture. First of all, it shows us that its inhabitants had a sophisticated system of labor divisions. They would have needed the city planners and leaders who designed and planned the construction. They had people to organize the laborers and secure building materials. Then, there would be the laborers themselves, who actually performed the construction. We do not know exactly what their power structure looked like, but it was likely highly stratified in order to accomplish so much urban building.
Interestingly, these cities demonstrate the importance of the egalitarianism that must have been practiced in Harappan culture. For instance, each house, regardless of how grand or modest it was, had access to drinking water and even rudimentary sewage systems. This indicates the possibility of social welfare within the society.
Also, the presence of highly planned cities that utilized advanced concepts of trigonometry and geometry in their layout indicates the importance of education, at least among the city planners themselves. That the cities were usually laid out in uniform neighborhoods and city blocks also indicates to us that precision and uniformity were probably valued concepts in their culture and society.
Since large cities tend to be the home of merchants and artisans, we can also infer that the Indus River Civilization had many of these. They must have had ample agriculture occurring outside the cities to feed these urbanites. It also indicates that trade was very important. This is further supported by many archeological finds of goods and products that were produced far from the Indus River Valley.
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https://www.ancient.eu/Indus_Valley_Civilization/