Five (panch) confluences (prayag) that bring forth the Ganga.
Vishnuprayag – Alaknanda and Dhauliganga.
Nandaprayag – Alaknanda and Nandakini.
Karnaprayag – Alaknanda and Pindari.
Rudraprayag – Alaknanda and Mandakini.
Devprayag – Alaknanda and Bhagirathi, becoming Ganga.
The namesake of the places refer to
Vishnu, Nanda – Krishna’s foster father, Karna – Kunti’s first son, Rudra – Shiva, Deva – the divine confluence.