According to Samudra Mandana's story in mythology, war between the gods and the Asuras took place to obtain Sagara. Then the Asuras took the plate of the immortality. Thus the devotees did not get the Amirtham. Following this, Mohini's incarnation Vishnu attracted Amrita and gave them to the gods.
Amirtham was given to Indira's son Jayantha. At that time, the four drops of Amirtham are believed to have fallen in Nashik, Ujjaini, Haridwar and Pragyaraj. This is why Kumbh Mela is celebrated in four places. According to the mythological story of the samudra manthana, there was a fight between the gods and the asuras for immortality.