Koshi is one of the fourteen zones of Nepal. The headquarters of Koshi Zone is Biratnagar. It is also its largest city. Other major cities of Koshi Zone are Inaruwa, Dharan, Dhankuta and Itahari. Its main rivers are the Arun, Tamor, and Sapta Koshi. Koshi has six districts. These are Bhojpur, Dhankuta, Morang, Sankhuwasabha, Sunsari and Terhathum.