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.