Like modern-day Indian businessmen, the Harappans had a huge domestic market to cater to. The climate around that time was conducive for growing a variety of crops in the region. Harappans are credited with being the earliest growers of rice and cotton. The agricultural surpluses ensured craft specialisation. And at its peak, the Indus was dotted with over 300 cities of varying sizes, supported by hundreds of towns and villages which supported a cottage industry.
Quality standards seems to have been strictly observed, resulting in uniformity of arts and craft.
It brought prosperity that saw the cities provide their citizens with the finest of drainage systems and reservoirs to supply water. And helped them evolve into one of the greatest civilisations ever. Archaeologists are known to stumble, but the kind of knocking Wheeler has taken over his Aryan invasion theory has few parallels. When the British archaeologist discovered a dozen skeletons in Mohenjodaro, he propounded a theory about the final massacre by marauding invaders that put an end to the Indus civilisation. When an Indian scholar told him of Hariyuppa being mentioned in the Rigveda, he took it to mean Harappa.