Between the sixth and fourth centuries BCE, Magadha ascended as the foremost mahajanapada, with modern historians attributing this transformation to several factors. Magadha boasted highly productive agriculture, benefitting from fertile lands and favourable climatic conditions. The region's accessibility to iron mines contributed to abundant resources for crafting essential tools and formidable weapons. Furthermore, the presence of elephants in Magadha's forests played a vital role in bolstering the strength of their military forces. Additionally, the strategic advantage of being situated along the Ganga and its tributaries offered Magadha a cost-effective and efficient means of communication, trade, and transportation. The combined influence of these factors propelled Magadha to become the dominant and powerful mahajanapada of its time.

According to the early Buddhist and Jaina writers what attributed to the powers of Magadha?

Policies of individuals- ruthlessly ambitious kings 

Early Buddhist and Jaina writers who wrote about Magadha attributed its power to the policies of individuals:  ruthlessly ambitious kings of whom Bimbisara, Ajatasattu, and Mahapadma Nanda are the best known, and their ministers, who helped implement their policies.