Ajatashatru (c. 492 – c. 460 BCE) was a king of the Haryanka dynasty of Magadha in North India. He was the son of King Bimbisara. He was contemporary with Mahavira and Gautama Buddha.He fought a war against Vajji, ruled by the Lichhavis, and conquered the republic of Vaishali. Ajatashatru followed policies of conquest and expansion. He defeated his neighbors including the king of Kosala; his brothers, when at odds with him, went to Kashi, which had been given to Bimbisara as dowry. This led to a war between Magadha and Kosala. Ajatashatru occupied Kashi and captured the smaller kingdoms. Magadha under Ajatashatru became the most powerful kingdom in North India.
After conquering Vaishali, Kasi and Kosala (Kaushala) Ajatasatru conquered 36 republican states surrounding his kingdom and firmly established the predominance of Magadha. Ajatashatru was monarch of a huge kingdom, which covered almost all of modern India's Bihar, Chandigarh, Haryana, Uttarakhand,Himachal Pradesh, Delhi, Uttar Pradesh, One fourth of north Madhya Pradesh, tip of Chhattisgarh, bit of Jharkhand, west Bengal
Ajatasatru, with the help of his two ministers Sunidha and Vassakāra, built a fort near the banks of the river
Ganges to strengthen the defense of Magadha and named it Pātali Grama(village). Later it developed into a city, which soon became popular as Pataliputra, now known as Patna, the capital of Bihar.According to Mahaparinirvana sutta, when Pataliputra was being erected, by chance the Buddha came there and praised the city of Pataliputra, and pointed to three things which could prove fatal to the city: fire, water and discord among the people.The account of Ajātaśatru's death recorded by historians is c. 461 BC. The account of his death differs widely between Jain and Buddhist traditions.