Megasthenes, a Greek historian who visited India during the reign of Emperor Chandragupta Maurya, mentioned six subcommittees in his book titled Indica. These subcommittees were known as the six committees of the Mauryan administration.

The six subcommittees mentioned by Megasthenes are:

1. Board of Revenue: This committee was responsible for the collection of taxes and revenue from the various provinces of the Mauryan Empire.

2. Military Board: This committee was responsible for the recruitment, training, and deployment of soldiers in the Mauryan army.

3. Board of Works: This committee was responsible for the construction of public works such as roads, bridges, and irrigation systems.

4. Board of Justice: This committee was responsible for the administration of justice in the Mauryan Empire.

5. Board of Accounts: This committee was responsible for maintaining the financial records of the Mauryan Empire.

6. Board of Censors: This committee was responsible for monitoring the behavior of government officials and ensuring that they were performing their duties in an ethical and efficient manner.

These subcommittees played a crucial role in the functioning of the Mauryan Empire and helped to ensure that the administration was efficient and effective. The system of subcommittees was a unique feature of the Mauryan Empire and was admired by foreign visitors such as Megasthenes.