The mela (gathering) is held on a rotational basis at four auspicious Hindu pilgrimage sites-Allahabad, Haridwar, Nashik-Trimbak and Ujjain. According to Hindu mythology, during the ‘Samudra Manthan’ i.e. churning of the ocean, ‘Amrit’ i.e. drink of immortality was produced and stored in a ‘Kumbh’ (pot). In the battle of the Devas and the Asuras, Lord Vishnu dropped drops of Amrit while transporting the Kumbh. These places are the four sites where the Kumbh Mela is held.
The mela is held once in three years at different places and at any given place after a time interval of twelve years. The exact dates are determined according to the zodiac positions of the Sun, Moon and the planet Jupiter. At Nashik and Ujjain, if the mela is held when a planet is in Leo (Simha in Hindu astrology), it is called as Simhastha Kumbh.
At Haridwar and Allahabad, Ardh-Kumbh Mela is held every sixth year and a Maha Kumbh takes place once in 144 years.
Maagh Kumbh is celebrated every year in the month of Maagh (JanFeb) in Allahabad.