Magadha

Magadha, an ancient kingdom of India was situated in what is now west-central Bihar state, in northeastern India. It was the nucleus of several larger kingdoms or empires between the 6th century BCE and the 8th century CE. The early importance of Magadha may be explained by its strategic position in the Ganges (Ganga) River valley, enabling it to control communication and trade on the river. The river further provided a link between Magadha and the rich ports in the Ganges delta.

Under King Bimbisara (reigned c. 543–c. 491 BCE) of the Haryanka line, the kingdom of Anga (eastern Bihar) was added to Magadha. Kosala was annexed later. The supremacy of Magadha continued under the Nanda (4th century BCE) and Mauryan (4th–2nd century BCE) dynasties; under the Mauryan dynasty the empire included almost the entire subcontinent of India. The early centuries CE saw the decline of Magadha, but the rise of the Gupta dynasty in the 4th century brought it once more to a position of preeminence. Not only did these imperial dynasties begin by establishing their power in Magadha but in each case Pataliputra (adjacent to modern Patna) was the imperial capital, thus adding to the prestige of Magadha.

Lively accounts of Pataliputra and Magadha are available in the Indica of the Greek historian Megasthenes (c. 300 BCE) and in travel diaries of the Chinese Buddhist pilgrims Faxian and Xuanzang (4th–5th and 7th centuries CE). Many sites in Magadha were sacred to Buddhism. Toward the close of the 12th century, Magadha was conquered by the Muslims.

(Source: https://www.britannica.com/place/Magadha)