The history of Kumbh Mela is at least 850 years old. It is believed that Adi Shankaracharya started it, but according to some legends, Kumbha started from the beginning of the sea churning. It has been told in the scriptures that the year of the earth is the day of the gods, so every twelve years, Kumbh is organized again at one place. The twelve years of the gods come after 144 years of the earth. It is believed that after 144 years, Kumbh is organized in heaven, so that year Mahakumbh is held on earth. Prayagraj has been designated as the real place for Mahakumbh.
The Kalash is called Kumbh which means pitcher. This festival is related to the nectar(amrit) in urn which came out during the sea churning. Once Indra and the gods fell weak due to the curse of Maharishi Durvasa, the demon who attacked and defeated the gods. All the gods together approached Lord Vishnu and told him everything. Then Lord Vishnu advised the gods to go against the demons and churn the Kshira Sagar and extract the nectar(Amrit). At the behest of Lord Vishnu, the entire deity engaged in an attempt to extract the nectar by making a treaty with the demons. At the behest of the deities, Indra's son 'Jayant' flew into the sky carrying the Amrit Kalash. The demons chased Jayant to fetch the nectar and after a while, they caught Jayant in the midway and there was a fierce battle between Dev and Demon for 12 days to take possession of the Amrit Kalash.
Some of its drops fell in the three rivers of the earth. Kumbh is organized at the place where these drops fell. The names of those three rivers are Ganga, Godavari and Kshipra. The nectar that came out in the churning fell at these places- Haridwar, Prayagraj, Ujjain and Nashik. Hence the Kumbh Mela has been held at these four places only after every three years. After 12 years, this fair returns to its first place. This is the reason that the Kumbh Mela is celebrated at these four places. Kumbh is divided into 4 parts. For example, if the first Kumbh is in Haridwar, then after 3 years, the second Kumbh is in Prayagraj and then the third Kumbh is in Ujjain after 3 years, and then after 3 years, the fourth Kumbh is in Nashik.
Jupiter and the Sun planets play an important role in deciding the date and place of the Kumbh Mela. The location and date of the fair are determined only by entering the zodiac signs of Jupiter and the Sun.
According to religious belief, all the sins of people who worship devoutly in Kumbh are cut off and they get salvation. Kumbh bathing is considered to be special because it is believed that on this day the gates of heaven worlds are opened on this day and thus bathing on this day gives the soul easy access to the higher realms.
If you are going to have a Kumbh bath, keep in mind that the bath has a special rule. If you are going to have a bath in Kumbh or a bath in a holy river even on normal days, then some things should be taken care of.