Along with agriculture and animal husbandry, trade and systematic management, and organisation of the trade are also essential factors for the prosperity of a state.
The guilds of the merchants and the artisans played a great role in the growth of the mahajanapadas into wealthy states.
These guilds had their own way of organisation and functioning.
Guilds had their own, strict rules. Hence, they had a stringent structure.
This stringent structure is perceived as one of the main reasons for the rise of the caste system.