Koshi, Gandaki and Karnali are main three big rivers of Nepal flowing from east, middle and western part of Nepal. Each river has its own history, culture and tradition, which is alike with most of other ancient river civilizations. Among them Koshi is the biggest river and its culture is known as the oldest one in Nepal. Varahakshetra, Chatara, Pindeswara and Ramdhuni of Nepal and Simheswor and Tarasthan of Bihar India are the centre of pilgrims and civilization in Koshi River basin. Because of its destructive nature, we cannot find the archaeological remains of old civilization at Sapta Koshi valley. However, Kichakbadh, Rajabirat Kshetra and Bideha are some of the famous centers of civilization near Koshi basin. This river is said the Kausiki Mata in ancient Samskrit texts. According to the Pauranic text of Hindus, it is originated from the sweat of Parvati and she is known as Parvati in religious aspect. Because of its destructive nature, people were always afraid from its flood and therefore, people planned to make dams in Koshi River from long ago. In this process Saptakoshi high dam project was prepared from the side of India at British India period. The main center of making this dam was in Nepal and more benefit goes to the Indian side from this project. Therefore, Koshi high dam project is in conflict between these countries. However, we can make a plan of a high dam based on equal benefit for the people of both countries and we can fulfill the necessities of the people of this region. This is one of the best ways of using unused resources and controlling harm from the flood of Koshi River. Arun River, the main branch of Saptakoshi originates from 7000 meters high altitude in Tibet and flows towards south. Different branches of Saptakoshi are originated from different mountains with different names and they are flowing towards southeast, southwest and direct south.