Subahs were the large provinces

Each subah had its own set of important officials (like finance and military officers), so the emperor’s orders could be carried out efficiently across different parts of the empire.
Subahs were usually divided further into smaller units (often called sarkars and parganas), which helped the government reach down to towns and groups of villages.
A key purpose of subahs was better revenue collection: officials could measure land, assess crops, and collect taxes in an organised way rather than relying only on local chiefs.
They also supported law and order and defence—keeping troops ready, maintaining forts, and responding quickly to rebellions or attacks.
A concrete example: Bengal was an important Mughal subah because it was wealthy from agriculture and trade; controlling it well meant strong income for the empire.

Thinking of subahs as “big administrative zones” helps explain how the Mughals managed such a large territory without running everything directly from the capital.