Nanda dynasty had full command over transportation & trade on the River Ganga. Chandragupta Maurya after killing the Nanda brothers (forgiving the old Emperor Mahapadma Nanda, who was his biological father) and considering the privilege of Emperor, had automatically got into control over that business.
The exclusive important effort in this way was to gain over Rakshasa Mantri, the Prime Minister of Nandas. Chandragupta's instructor & King-maker, Chanakya encouraged his protege to take (his opponent) Rakshasa on his team, as he was proficient at administrating the Empire properly. Rakshasa was so faithful to his past mentors (though proud & inefficient) that he planned to eliminate Chandragupta Maurya, utilizing his nubile child as a ploy or imitation. When all attempts deserted, Chandragupta requested to his real soul, inevitability & persuaded him to take over the obligation of the Imperial government. The trade & that too on the waterway of River Ganga was a section of this case. With the government in strong hands, the Emperor was free to draw out his army operations as in the suspension the territorial Satraps were interesting ideas of cutting loose from the Empire.
