"Kumbh Mela (the festival of the sacred Pitcher) is the largest peaceful congregation of pilgrims on earth, during which participants bathe or take a dip in a sacred river. Devotees believe that by bathing in the Ganges one is freed from sins liberating her/him from the cycle of birth and death. Millions of people reach the place without any invitation. The congregation includes ascetics, saints, sadhus, aspirants-kalpavasis and visitors. The festival is held at Allahabad, Haridwar, Ujjain and Nasik every four years by rotation and is attended by millions of people irrespective of caste, creed or gender. Its primary bearers, however, belong to akhadas and ashrams, religious organizations, or are individuals living on alms. Kumbh Mela plays a central spiritual role in the country, exerting a mesmeric influence on ordinary Indians. The event encapsulates the science of astronomy, astrology, spirituality, ritualistic traditions, and social and cultural customs and practices, making it extremely rich in knowledge. As it is held in four different cities in India, it involves different social and cultural activities, making this a culturally diverse festival. Knowledge and skills related to the tradition are transmitted through ancient religious manuscripts, oral traditions, historical travelogues and texts produced by eminent historians. However, the teacher-student relationship of the sadhus in the ashrams and akhadas remains the most important method of imparting and safeguarding knowledge and skills relating to Kumbh Mela."
Source: UNESCO Intangible Cultural Heritage
Naga Baba Kumbh Festival. I bought this postcard when I was travelling in India.