Wikipedia
Magadha formed one of the sixteen Mahajanapadas ( Sanskrit: "Great Countries") of ancient India. The core of the kingdom was the area of Bihar south of the Ganges; its first capital was Rajagriha (modern Rajgir), then Pataliputra (modern Patna). Rajagriha was initially known as 'Girivrijja' and later came to be known as so during the reign of Ajatashatru. Magadha expanded to include most of Bihar and Bengal with the conquest of Licchavi and Anga, respectively, followed by much of eastern Uttar Pradesh and Odisha. The ancient kingdom of Magadha is heavily mentioned in Jain and Buddhist texts. It is also mentioned in the Ramayana, the Mahabharata and the Puranas. A state of Magadha is recorded in Vedic texts much earlier in time than 600 BCE.
The earliest reference to the Magadha people occurs in the Atharvaveda, where they are found listed along with the Angas, Gandharis and Mujavats. Magadha played an important role in the development of Jainism and Buddhism, and two of India's greatest empires, the Mauryan Empire and Gupta Empire, originated in Magadha. These empires saw advancements in ancient India's science, mathematics, astronomy, religion, and philosophy and were considered the Golden Age of India. The Magadha kingdom included republican communities such as the community of Rajakumara. Villages had their own assemblies under their local chiefs called Gramakas. Their administrations were divided into executive, judicial, and military functions.