Sarayu is a river that flows through the Indian states of Uttarakhand and Uttar Pradesh. This river is of ancient significance, finding mentions in the Vedas and the Ramayana. The Sarayu forms at the confluence of the Karnali (or Ghaghara) and Mahakali (or Sharda) in Bahraich District. The Mahakali or Sharda forms the Indian-Nepalese border. Ayodhya is situated on the banks of river Sarayu. On Ram Navami, the festival that celebrates the birthday of Lord Rama, thousands of people take a dip in the Sarayu River at Ayodhya. According to Ramayana , the Sarayu flowed beside the ancient city of Ayodhya, which is in the modern day Uttar Pradesh. It was a tributary of the Gogra. This Sarayu played a vital role for the city and life of Ayodhya, and according to the great Sanskrit epic Ramayana, is where Rama, the seventh Avatar of Vishnu immersed himself to return to his eternal, real Mahavishnu form, when he retired from the throne of Kosala. His brothers Bharata and Shatrughna also joined him, as did many devo