The mahajanapadas on the Gangetic plains were all monarchies. Vedic orthodoxy was an established practice in these kingdoms. The kingship was hereditary and the succession was in most cases based on the law of primogeniture. 

• The king was assisted by councils called parishad and sabha. The councils were advisory in nature. The king appropriated the agricultural surplus through land revenue apart from a few other taxes.  
• Bali was a tax imposed based on the area of cultivable land. Bhaga was obtained as a share of the produce. Kara and Shulka were some of the other taxes collected during this period.  

• Thus the king raised revenue through taxes to maintain an elaborate administrative structure and an army. 

Source: Tamil Nadu state board