Mandar hill is extremely sacred in the Hindu Mythology. The Skanda Purana records the history of the famous Amrit Manthan ( the churning of the ocean ). Due to this mythical association, the hill has assumed considerable religious significance and had been a place of pilgrimage up till now.
The Mandar Mahatmya, a portion of the Skanda Purana, describes Mandar Hill. It is said that Raja Chhatra Sen of the Chol tribe, who lived before the time of the Muhammadans, erected the oldest temples at the summit. Some of the carvings on the rocks are taken by some to be shell writings. Mandar Hill is also very important as it has the unique image of Vishnu, probably the only sculpture in Bihar where Vishnu, in his man-lion incarnation, has not been shown as tearing Hiranyakashipu. The portrait is 34 inches high and made of black stone. It belongs to the Gupta period.
An inscription of Gupta King Adityasena has been discovered on the ‘Mandar Hill. This inscription relates that both he and his queen Sri Konda Devi had installed an image of Narahari (Man-lion), an incarnation of Vishnu, on the hill, and that the queen performed an act of piety by excavating a tank, known as Papa Harini, at the foot of the said hill. Papa Harini was also known as Manohar Kund.
In the memory of the 12th Jain Tirthankara Vasupujya who attained nirvana here, a Jain temple is also built on top of this hill.