The kingdom of Magadha rose to pre-eminence during the period of Bimbisara
and became the first great empire in India by the time of Nanda. Magadha
occupied a strategic position of geographical importance. It was bound on
the north and west by the river Ganges and Son on the south by the spurs
of the Vindhyas and on the east by the river Champa. In this way it was
safe from all four sides. Even its two capitals Rajgriha and Patliputra
were situated at a strategic position from a geographic viewpoint. Its
first capital Rajagriha was surrounded by five hills forming a natural
defence. While its second capital Pataliputra being at the junction of the
Ganges and the Son had natural means of defence.
Natural resources were also favourable to Magadha. The rich iron deposits were situated not far away from Rajgir. It was from this that its rulers could make effective and strong weapons. Its adversaries lacked reserves of iron ore and could not equip themselves with weapons of such high quality. Hence they were easily defeated by Magadhan rulers. Thus the local iron ore deposits made possible better implements and weapons and a profitable trade in iron.
The land of Magadha was also fertile which yielded rich harvests. Heavy rainfall made the land more productive even without irrigation. They produced varieties of paddy which are mentioned in the early Buddhist texts. Land taxes could be kept high which proved to be regular and substantial source of income to the state without which the maintenance of a big army could not be possible and the empire could neither be built nor consolidated. Neighbouring forests provided timber for buildings and elephants for the army.