Kumbh Mela or Kumbha Mela inscribed on the UNESCO's Representative List of Intangible Cultural Heritage of Humanity, is a mass Hindu pilgrimage of faith in which Hindus gather to bathe in a sacred or holy river. Traditionally, four fairs are widely recognized as the Kumbh Melas: the Haridwar Kumbh Mela, the Allahabad Kumbh Mela, the Nashik-Trimbakeshwar Simhastha, and Ujjain Simhastha. These four fairs are held periodically at one of the following places by rotation: Haridwar, Allahabad (Prayaga), Nashik district (Nashik and Trimbak), and Ujjain. The main festival site is located on the banks of a river: the Ganges (Ganga) at Haridwar; the confluence (Sangam) of the Ganges and the Yamuna and the invisible Sarasvati at Allahabad; the Godavari at Nashik; and the Shipra at Ujjain. Bathing in these rivers is thought to cleanse a person of all their sins.
At any given place, the Kumbh Mela is held once in 12 years. There is a difference of around 3 years between the Kumbh Melas at Haridwar and Nashik; the fairs at Nashik and Ujjain are celebrated in the same year or one year apart. The exact date is determined, as per Vikram Samvat calendar and the principles of Jyotisha, according to a combination of zodiac positions of the Jupiter, the Sun and the Moon. At Nashik and Ujjain, the Mela may be held while a planet is in Leo (Simha in Hindu astrology); in this case, it is also known as Simhastha. At Haridwar and Allahabad, an Ardha ("Half") Kumbh Mela is held every sixth year; a Maha ("Great") Kumbh Mela occurs after 144 years.
The priests at other places have also claimed their local fairs to be Kumbh Melas. For example, the Mahamaham festival at Kumbakonam, held once in 12 years, is also portrayed as a Kumbh Mela.
Kumbh Mela at Allahabad
when Jupiter is in Aries or Taurus and Sun and Moon are in Capricorn during the Hindu month of Magha (January-February).
Kumbh Mela at Haridwar
when Jupiter is in Aquarius and Sun is in Aries during the Hindu month of Chaitra (March-April).
Kumbh Mela at Ujjain
when Jupiter is in Leo and Sun is in Aries, or when all three are in Libra during the Hindu month of Vaisakha (April-May).
Kumbh Mela at Nasik
when Sun and Jupiter are in Leo during the Hindu month of Bhadraprada (August-September).