According to religious beliefs, the entry of the Sun into Capricorn (Makar Rashi) marks the beginning of the sacred month-long Kalpavasa at Prayagraj, offering devotees spiritual rewards equivalent to an entire kalpa (a day of Brahma). Ancient scriptures such as the Mahabharata and Ramcharitmanas also mention this ritual, emphasizing its spiritual significance.
During Kalpavasa, pilgrims, known as Kalpavasis, live on the riverbanks, sleeping on the ground, eating only one meal a day or fasting entirely, and bathing in the holy waters of the Ganga thrice daily. As per the Mahabharata, the spiritual merit attained through a century of penance without consuming food equals the merit of observing Kalpavasa during the auspicious month of Magha at the confluence of the Ganga, Yamuna, and Saraswati rivers.
It is believed that in the month of Magha, all sacred pilgrimage sites converge at Prayagraj to pay homage to their spiritual king. Bathing at the confluence (Sangam) during this time is said to bestow eternal blessings, making Kalpavasa a sacred tradition that attracts millions of devotees.
The tradition of Ardh Kumbh and Kalpavasa is unique to Prayagraj and Haridwar. Historians trace the first documented mention of the Kumbh Mela to the Mughal-era text Khulasat-ut-Tawarikh in 1665. However, many scholars dispute this, citing ancient scriptures and Vedic texts to argue that the Kumbh Mela has existed for millennia.