Shishunag Dynasty ( 412-325 BCE)
Shishunag was an amatya of the last ruler Nagadasak. He temporarily shifted the capital to Vaishali. Shishunaga defeated the last ruler King Pradotya of Avanti, ending a 100-year-old rivalry between Magadha and Avanti. He also annexed Kosala.
Shishunag was succeeded by his son Kalashok (kakavarna). He conducted the Second Buddhist Council at Vaishali. Kalasoka shifted the capital back to Pataliputra. He was killed in a palace revolution that brought the Nanda dynasty to the throne.
Nanda Dynasty (345-321 BCE)
The Shishunag dynasty was succeeded by the Nands (the first non-Kshatriya).
Mahapadmananda: The Puranas call him a shudra belonging to the barber clan, while the Buddhist tradition calls him Ugrasen because of his large army. He claimed to be Ekarat, the sole sovereign who destroyed all other ruling princes and sarva Kshatrantaka, uprooter of the Kshatriyas. Hathigumpha inscription of Kharvela, mentions a king named Nanda who built a canal and conquered Kalinga.
Dhanananda: He was ruling Magadha at the time of Alexander’s invasion. He was a powerful king who ruled over the eastern people and the people of the lower Ganga valley. He is believed to be an arrogant and oppressive ruler, his greed and exploitation made him unpopular, and ultimately Chandragupta Maurya under the guidance of Kautilya, uprooted the Nanda rule and set up the Maurya empire.
Factors responsible for the success of Magadha
Geographical position: Rich deposits of copper and iron were available near the Magadha region which could help in making better weapons and agricultural implements. Girivraja or Rajagrih, the early capital, was surrounded by five hills, which helped it to provide natural fortification.
Connectivity: The Ganga and its tributaries connected this kingdom with important trade routes. Pataliputra was situated at the confluence of the Ganges, the Gandak, and the Son, and this provided easy transport in all directions.
Superior military organization: The huge availability of resources allowed Magadhan rulers to maintain a large army. Magadh was the first state to use elephants on a large scale.
Socio-cultural factors: The people of Magadha were materialistic in outlook and unorthodox in character and rulers thus invested their time and resources in the socio-economic progress. However, in the later period, it underwent ethnic admixture.
Role of Magadhan ruler: The aggressive as well as pragmatic policies of some Magadhan rulers contributed significantly to the success of Magadh imperialism. For example- the matrimonial alliance policy of Bimbisara and the aggressive policy of Ajatshatru.
References:
A History of Ancient and Early Medieval India, Upinder Singh
Ancient and Medieval India, Poonam Dalal Dahiya
Higher Secondary First year, Tamil Nadu Board
Prateek Nayak Notes