Hello aspirant

.The sixth century BCE is often regarded as a major turning point in early Indian history.
.It is an era associated with early civilisation, the growing use of gold and silver, the development of paper currency, etc.
.It also witnessed the growth of diverse systems of thought, including Buddhism and Jainism.

All the above factors were responsible for urbanization in sixth century BCE

Hi Aspirant,

The main factors that led to urbanization is the invention of Iron.With the invention of iron Forest clearance became very easy.Since the use of iron made the field clear, people began cultivating more land. They learnt the practice of cultivating two-three crops in a year. This led to urbanization during 6th century BC.

Hope it helps!!