Why didn't the indus valley ever unify?

Answer 1

The Indus Valley civilization did not unify due to its vast geographical expanse, which included diverse environments and resources that led to varied local cultures and practices. Additionally, the region's city-states, such as Harappa and Mohenjo-Daro, operated independently with their own governance and trade systems, reducing the incentive for political unification. The absence of a dominant political or military power and potential external threats may have also contributed to this fragmentation. Furthermore, the decline of the civilization around 1900 BCE further prevented any efforts toward unification.