According to astrologers, the `Kumbha Fair` takes place at Hardwar when the planet Jupiter enters Aquarius and the Sun enters Aries during the Hindu month of Chaitra. It takes place at Allahabad, when Jupiter is in Aries or Taurus and the Sun and Moon are in Capricorn during the Hindu month of Magha (January-February); at Nasik, when Jupiter and the Sun are in Leo in the Hindu month of Bhadrapada (August-September). It takes place at Ujjain, when Jupiter is in Leo and the Sun is in Aries, or when Jupiter, the Sun, and the Moon are in Libra during the Hindu month of Vaisakha (April-May). Each twelve-year cycle includes the Maha (great) Kumbha Mela at Prayag, attended by millions of people, making it the largest pilgrimage gathering around the world. Thus, Kumbha Mela occurs at each of the four locations.

Prayag (near Allahabad, in Uttar Pradesh) at the confluence of three rivers Ganga, Yamuna and Saraswati.

Haridwar (in Uttar Pradesh) where the river Ganga enters the plains from Himalayas.

Ujjain (in Madhya Pradesh), on the banks of Ksipra river and

Nasik (in Maharashtra) on the banks of Godavari River.

The observance of Kumbha Mela is based upon the story of "Amrit manthan". The legend says that the gods were cursed by a sage and became emaciated and wished to regain their old vigour by feasting on Amrita or the cream of the milk ocean. The weak gods could not churn the ocean by themselves and enlisted the support of the Asuras, their inveterate enemies, by promising to them a portion of the amrit. As the churning progressed, the ocean began to yield its treasures one by one, and lastly appeared the sage Dhanwantari with the coveted Kumbha or jar of nectar. The Asuras were physically stronger and seized the Kumbha, but one of the gods assumed the form of a rook and whisked away the jar, with the Asuras in hot pursuit. The bird on its way to paradise is said to have taken rest at Nasik, Ujjain, Prayag and Hardwar.

The rook took twelve days to reach paradise from the milk ocean, and as each divine day is reckoned equivalent to an earth year, the Kumbha Mela is celebrated once in twelve years at each of these four places. According to another version of the legend, as the gods and the Asuras struggled for the possession of Kumbha, some nectar, spilt from the jar, fell at the four places mentioned above. The Mela is not held at all the four places on the same date but in turn and hence we have a Kumbha Mela every three years or so. Prayag at the confluence of the rivers Ganges and Yamuna is particularly holy, and the riverbed here is extensive and can easily hold millions of pilgrims.

Kumbha Mela originated as a meeting place for the main religious heads in the country to exchange ideas. Chinese pilgrim Hiuen Tsang, who visited India in the seventh century of the Christian era, described of a similar festival at Prayag, presided by King Harsha. King Harshvardhan arranged the Kumbha Mela as a great fair and meeting of saints, sages and sects, called the Mahamoksha Parishad. It is not clear whether the festival celebrated in Harsha`s time was actually Kumbh Mela; for the festival over which, Harsha presided came every five years and Kumbh Mela at present comes once in 12 years.

Then Adi Shankaracharya, around the eighth century AD, arranged the Mela to be close to what we still see today. He directed the ten main Akharas or religious sects, to assemble regularly at the Kumbha Mela in order to maintain contact with each other, as well as have religious discourses and provide spiritual guidance for the masses. It is also believed that Adi Shankaracharya established the sects of the babas in order to help defend the faith. These babas were expected to have the ability to easily give up their lives, if necessary, in order to preserve the culture. Being followers of Adi Shankaracharya, they were mostly Shaivites.

Kumbha Mela is attended by millions of people on a single day. A ritual bath at a predetermined time and place is the major event of this festival. Other activities include religious discussions, devotional singing, mass feeding of holy men/women and the poor, and religious assemblies where doctrines are debated and standardized. Kumbha Mela (especially the Maha Kumbha Mela) is the most sacred of all the Hindu pilgrimages. Thousands of holy men/women (monks, saints, sadhus) grace the occasion by their presence. The holy saints pass by on their various and sundry conveyances -elephants, horses, palanquins, chariots, cars, and camels. The musicians and dancers perform in the midst of the cacophony of gongs, drums, trumpets, conch shells and bells.

Prayag Snan or bathing in the confluence of the river Ganges and Jamuna is of great importance. It is believed, that it washes away all the sins and the cycle of rebirth and death ends as the soul becomes one with God Almighty. It is mentioned in the Rig-Veda that the Ganga and Yamuna Rivers are like white and blue-colored streams that mingle at Prayag, which give immortality to humans when they bathe in it. The Brahma Purana mentions that bathing in the month of Magh at the bank of the Ganga and Yamuna at Prayaga gives the results of millions and millions of Ashvamedha rituals.