Why (as far as I know) was all the chert obtained from the Rohri Hills and distributed everywhere else? What does this tell us about the nature of the Harappan economy and society? Submitted by Gharial Abramnova from school student questions
Such raw materials were of immense importance to all the civilized societies of the period (and other periods), either for their practical use (eg metals for tools, timber for houses and ships) or for social, political and religious display (eg adorning temples). In terms of the efforts involved, the Harappans were fortunate in being able to obtain many of their raw materials far more easily than many of their contemporaries: the hills and mountains surrounding the Indus region on 2-3 sides were neighbouring sources of many of the minerals they required and were inhabited by friendly cultures, whereas the Mesopotamians, for example, were frequently in conflict with the peoples of the neighbouring regions from or through which they had to obtain raw materials.
The flint (chert) from the Rohri Hills is of exceptional quality so was better for making tools than that from the many sources closer to many Harappan communities. The universal use of Rohri Hills flint during the Harappan period, and the reliance on more local sources before and after, does indeed give an important insight into Harappan economy and society: it means that during the Harappan period there was a system in place that ensured that the best material was made available to all. This implies a well organised and well integrated distribution network, at the very least, and I would argue that it also implies a strong state and efficient bureaucracy, controlling mining and issuing flint (and other materials) to communities and individuals.
There is a very interesting dissertation by Randall Law that was just published and he has identified the places where they procured their raw materials. According to him, they used a variety of resources, some nearby and others at greater distances and changed their preferred sources over time. They were expert craftsmen and I believe through working with raw materials, they identified the best material for what they wanted to accomplish. They must as well have aesthetic concerns, a preference for grey or brown chert for example, dictating which place to get the source. And also did they have relationships with people near those sources that facilitated the trade and procurement. I don’t think this trading was done through a centralized leader, but more likely by networks of people who knew where the sources were (word of mouth or in their travels) and had connections to people with whom they traded. Or perhaps they paid them in some way, exchanged the raw materials for objects they produced or in some other manner.
Why do we go to such extraordinary lengths (and depths) to obtain petroleum? Raw materials of one kind or another have formed the basis for human technology for hundreds of thousands of years – to be made into tools for obtaining food and to serve more purely "cultural" purposes (social, ideological, political). Chert was obtained from other sources, but Rorhi chert was of exceptionally high quality and thus prized by knappers. Because it is well preserved in the archaeological record, such raw materials and the resulting manufactured artefacts have been studied extensively. Dr. Randy Law has located many of the sources of the stone found in Indus sites; these come from a huge area surrounding the Indus Valley itself, and it was probably to ensure a supply of such resources that the Indus people sent out expeditions to and maintained relationships with peoples in these resource areas. As you know, once you are used to using something, you want to make sure you continue to be able to use it and to replace it if necessary. See also the comments on trade and exchange above.
This tells us that there was an engagement in the procurement of materials and tools in the sphere of the public economy, not the individual household or village.