According to the Indian Almanac the full moon day of Kartik Purnima which usually falls in November is one of the most auspicious of days. A number of big fairs are held at important paces of pilgrimage. The Harihar Chhetra Mela near Sonepur is one of the biggest fairs held in India and is also the biggest cattle fair in Asia.

Sonepur is located in there Saran district in the northern part of Bihar. This district shaped like a triangle is demarcated by three mighty rivers – the Ganga, Gandak and Ghagra. Sonepur stands on the confluence of the Ganga and Gandak.

Like so many places of pilgrimage in India Sonepur also has its legend. It involves two kings both of whom were turned into animals – a crocodile and an elephant – by the curse of sages who were offended by them. Those days this area was supposed to have been girdled by hills with three towering peaks and a lake in the centre. Once, while bathing in the lake with a party of women, a Gandharva chief named Huhu made fun of Dewala Muni by playfully pulling his leg. The ire of the sage took the form of a curse that turned Huhu into a crocodile. The other accursed person was Indradyumna, a king of the Pandyas who was of a very pious nature but had offended the powerful sage, Agastya. The king had failed to notice the sage as he was in meditation when the sage visited him. The curse of the enraged Agastya turned Indradyumna into an elephant who took refuge in the woods surrounding the lake.

One day while the elephant came with a herd to the lake to bathe, the gandharva-turned-crocodile caught his leg in its powerful jaws. Not to be taken lightly, the king of elephants tried to pull the crocodile up on the bank in an effort to crush him under his feet. A mighty battle ensued which was joined by other crocodiles and elephants. The contest went on for thousands of years without any one being able to overpower the other. But ultimately the King Elephant weakened and prayed to the supreme god Vishnu (Hari) to save him. His prayer was answered and Vishnu cut down the crocodile with his chakra (disc). The touch of the chakra, however, released Huhu from the curse and he went to heaven. Vishnu also released Indradyumna from his curse by touching his forehead and took the king to His abode, Vaikuntha.

The temple of Harihar Nath is naturally the main objective of the visitors to the fair after they have taken their ritual bath in the swirling waters of the Gandak. The original temple is believed to have been built by Lord Rama on his way to the court of King Janak to win Sita. The age and origin of the present temple has puzzled scholars but it is supposed that Raja Man Singh had it repaired. The builder of the present temple was Raja Ram Narain, a prominent figure during the late Mughal period. The Birlas recently conducted repairs and extension works. As in many other famous places of worship, a number of smaller temples of other deities surround the temple of Harihar Nath Mahadeo.

When the pujas and the ablutions are over, the visitors abandon themselves to the various attractions offered in and around the sprawling mela ground. The village folk, particularly the women, are attracted to the array of shops selling all sorts of merchandise. The area that attracts all, however, is the one where the elephants are lined up for sale. Sonepur Fair is the only one where such a large number of elephants are sold. These are mainly purchased by different forest departments and people involved with logging operations. Apart from elephants, a large number of cattle and horses are also brought to the fair for sale.

The Sonepur Fair is of great antiquity and in olden times would attract traders from as far as Central Asia. Like the origin of the Harihar Nath Temple, the inception of the Sonepur Fair is lost in the labyrinth of time. The site of the present fair was originally at Hajipur while only the pujas used to be offered at the temple at Sonepur. During the reign of the Mughal emperor Aurangzeb, the fair was shifted to Sonepur. During the period of British rule, the European indigo planters used it as an occasion for social and sports gathering. The fair continues for about fourteen days but the few days before, during and after the Kartik Purnima draw the maximum crowds. The sleepy mango groves of the fair ground turns into a wonderland, sure to overwhelm the sophisticated urban visitor as well as the simple rural folk.