Question: kosi is a tributary of?
Answer: It is a major tributary of the Ganges. One major tributary of the Koshi is the Arun, much of whose course is in Tibet. This river is mentioned in the epic 'Mahabharata' as Kausiki. Seven Koshis join together to form the 'Saptakoshi River,' or 'Sapt Koshi,' which is popularly known as the Koshi.