Explanation:

The Mauryas created for the first time a well-organised state machinery, which operated in the heart of the empire.On the other hand their conquest opened the doors for trading and missionary activities. Contact established by administrators, traders and Jaina and Buddhist monks led to the spread of the material culture of the Gangetic basin to the areas situated on the periphery of the empire.
The new material culture in the Gangetic basin was characterised by intensive use of iron, plenty of punch-marked coins, abundance of beautiful pottery called Northern Black Polished ware, introduction of burnt bricks and ringwells, and above all the rise of towns in north-eastern India. (Phase of Urbanisation)A Greek writer called Arrian states that it is not possible to record with accuracy the number of cities on account of their multiplicity.