During the Vedic Age, the Angutara Nikaya, a Buddhist scripture, mentions the emergence of 16 great kingdoms or Mahajanapadas in India at the beginning of the 6th century BCE. These Mahajanapadas arose due to socio-economic, religious, and political developments, particularly in eastern Uttar Pradesh and western Bihar during the 6th to 4th centuries BCE. The region saw a flourishing of agriculture, thanks to the fertile lands, and an increase in iron production due to the abundance of iron ore. This led to the expansion of the territories of the Janapadas, or small kingdoms, which later became known as the highly developed regions of the Mahajanapadas.
The 16 Mahajanapadas that emerged before the rise of Buddhism in India were:
Over time, the smaller or weaker kingdoms and republics were eliminated by the stronger rulers. In the 6th century, only four powerful kingdoms remained: Magadha, Avanti, Kosala, and Vatsa. Eventually, all of these were annexed to or became part of the Magadha kingdom.
Most of the Mahajanapadas were monarchies, but some were republics known as Ganas or Sanghas. These Ganasanghas had a government by assembly and an oligarchy within the assembly. Vajji was a significant Mahajanapada with a Sangha form of government. The founders of Jainism and Buddhism came from republican states.
Each Mahajanapada had a capital city and many had forts built around them for protection from other kings. Regular armies were maintained by the Rajas, who also collected taxes from the people. The tax on crops was usually 1/6th of the produce, known as Bhaga or share. Craftsmen, herders, hunters, and traders were also taxed.
Agriculture underwent two major changes in this period: the growing use of iron ploughshares, which increased production, and the transplanting of paddy, in which saplings were grown and planted in the fields instead of scattering seeds on the soil. This greatly increased production but also increased the workload.
The use of iron tools in agriculture and military, along with the rise of urbanization, contributed to the socio-economic development of the Mahajanapadas. The availability of iron ore in large quantities led to an increase in iron production, which in turn led to the expansion of the Janapadas through the use of iron weapons. The development of trade also played a role in the growth of the Mahajanapadas.
During this period, the political center shifted from the west of the Indo-Gangetic plains to the east due to the more fertile land and closer proximity to iron production centers in this region. The eastern region also received more rainfall and had more rivers, contributing to its better fertility.
The rise of the Mahajanapadas was also influenced by religious and political developments. The emergence of new religions such as Jainism and Buddhism, and the teachings of their founders, Mahavira and Gautama Buddha, respectively, had a significant impact on the political structure of the Mahajanapadas.
In addition, the rise of the Magadha kingdom, with important rulers such as Bimbisara and Ajatashatru, played a crucial role in the political history of the Mahajanapadas. The Magadha kingdom eventually annexed or absorbed the other three powerful kingdoms of Avanti, Kosala, and Vatsa.
The emergence of the Mahajanapadas in India during the Vedic Age was a result of various socio-economic, religious, and political developments. The growth of agriculture and iron production, along with the rise of urbanization and the development of trade, contributed to the expansion of the Janapadas into the highly developed regions known as the Mahajanapadas. The rise of new religions and the emergence of powerful kingdoms such as Magadha also played a role in the history of the Mahajanapadas. This period, also known as the era of second urbanization, saw significant changes in agriculture and the political structure of the region.