The festival is traditionally credited to the 8th-century Hindu philosopher and saint Adi Shankara, as a part of his efforts to start major Hindu gatherings for philosophical discussions and debates along with Hindu monasteries across the Indian subcontinent. However, there is no historical literary evidence of these mass pilgrimages called “Kumbha Mela” prior to the 19th century. There is ample evidence in historical manuscripts and inscriptions of an annual Magha Mela in Hinduism – with periodic larger gatherings after 6 or 12 years – where pilgrims gathered in massive numbers and where one of the rituals included a sacred dip in a river or holy tank. According to Kama MacLean, the socio-political developments during the colonial era and a reaction to Orientalism led to the rebranding and remobilisation of the ancient Magha Mela as the modern era Kumbh Mela, particularly after the Indian Rebellion of 1857.
The weeks over which the festival is observed cycle at each site approximately once every 12 years based on the Hindu luni-solar calendar and the relative astrological positions of Jupiter, the sun and the moon. The difference in Prayag and Haridwar festivals is about 6 years, and both feature a Maha (major) and Ardha (half) Kumbh Melas. The exact years – particularly for the Kumbh Melas at Ujjain and Nashik – have been a subject of dispute in the 20th century. The Nashik and Ujjain festivals have been celebrated in the same year or one year apart, typically about 3 years after the Allahabad / Prayagraj Kumbh Mela. Elsewhere in many parts of India, similar but smaller community pilgrimage and bathing festivals are called the Magha Mela, Makar Mela or equivalent. For example, in Tamil Nadu, the Magha Mela with water-dip ritual is a festival of antiquity. This festival is held at the Mahamaham tank (near Kaveri river) every 12 years at Kumbakonam, attracts millions of South Indian Hindus and has been described as the Tamil Kumbh Mela. Other places where the Magha-Mela or Makar-Mela bathing pilgrimage and fairs have been called Kumbh Mela include Kurukshetra, Sonipat, and Panauti (Nepal).
The Kumbh Melas have three dates around which the significant majority of pilgrims participate, while the festival itself lasts between one and three months around these dates. Each festival attracts millions, with the largest gathering at the Prayag Kumbh Mela and the second largest at Haridwar.[20] According to the Encyclopædia Britannica and Indian authorities, more than 200 million Hindus gathered for the Kumbh Mela in 2019, including 50 million on the festival’s most crowded day. The festival is one of the largest peaceful gatherings in the world, and considered as the “world’s largest congregation of religious pilgrims”. It has been inscribed on the UNESCO’s Representative List of Intangible Cultural Heritage of Humanity. The festival is observed over many days, with the day of Amavasya attracting the largest number on a single day. The Kumbh Mela authorities said that the largest one-day attendance at the Kumbh Mela was 30 million on 10 February 2013, and 50 million on 4 February 2019.