The Phalgu or Falgu, a river that flows past Gaya, India in the Indian state of Bihar, is a sacred river for Hindus and Buddhists. In ancient scriptures, it is called the Nairañjanā in Sanskrit.
The portion of the course of the Phalgu flowing by Gaya is sacred to the Hindus. It is the first holy site visited by the pilgrim and here his first offering must be made for the souls of his ancestors. According to the Gaya Mahatmya, which forms part of the Vayu Purana, the Phalgu is the embodiment of Vishnu himself. One tradition states that it formerly flowed with milk.
There is a reference to the city of Gaya and the Phalgu in the Ramayana in which it says that Sita had cursed the Phalgu River. There is an interesting story and the mythology states that on account of this curse, the Phalgu lost its water, and the river is simply a vast stretch of sand dunes.According to tradition, in the absence of Rama, his wife Sita offered pinda on its banks to Dasharatha father of Rama.
The story goes that Rama, along with his brothers and Sita, came to Gaya to perform the sacred rites for his father, Dasaratha. When the brothers were bathing in the river, Sita was sitting on the banks, playing with the sand. Suddenly, Dasaratha appeared out of the sand, and asked for the Pindam, saying he was hungry. Sita asked him to wait till his sons returned, so that she could give him the traditional Pindam of rice and til. He refused to wait, asking her to give him pindams made of the sand in her hand.
Having no other option, she gave him the Pindam he desired with five witnesses – the Akshaya Vatam, the Falguni River, a cow, a Tulsi plant and a Brahmin. Soon, Rama returned and started the rituals. In those days apparently, the ancestors would arrive in person to collect their share, and when Dasaratha did not appear, they wondered why. Sita then told them what had happened, but Rama could not believe that his father would accept pindams made of sand. Sita now mentioned her witnesses, and asked them to tell Rama the truth.
Among the five, only the Akshaya Vatam took her side and told the truth, while the others lied, trying to take Rama’s side. In her anger, Sita cursed all of them thus: the Falguni river henceforth would have no water at Gaya; the Cow would no longer be worshipped from the front as all others are- only its backside would be worshipped; there would be no more Tulsi plants at Gaya and the Gaya Brahmins would never be satisfied, they would always be hungry and crave more and more. She then blessed the Akshaya Vatam saying that all who came to Gaya would perform the Pinda pradaanam at the Akshaya Vatam too.