Between the 6th and 4th century BCE, Magadha became the most important mahajanapada. The possible reasons could be:
- It was a region which was highly productive and hence surplus production was suitable for maintaining huge army.
- Magadha had huge resource of Iron. This metal was used both for weapons and tools. Latter increased the productivity of the land and former increased the offensive power.
- Elephants an important part of the warfare were found in abundance.
- Moreover geographical location make it impregnable as fort. As it was surrounded by rivers. These rivers also played a role in movement of troops.
- Early Buddhist and Jaina writers who wrote about Magadha attributed its power to the policies of a number of ruthlessly ambitious kings of whom Bimbisara, Ajatashatru and Mahapadma Nanda are the best known.