Definition
Kosi Zone (कोशी अञ्चल), also spelled Koshi Zone, was one of the fourteen administrative zones of Nepal until the country’s 2015 restructuring, which replaced zones with provinces.
Overview
Located in the eastern part of Nepal, Kosi Zone covered an area of approximately 9,669 km² (3,733 sq mi) and had a recorded population of 2,335,047 in the 2011 census, yielding a density of about 242 inhabitants per km². The zone’s administrative headquarters and largest city was Biratnagar, a major industrial centre. Other notable towns included Inaruwa, Dharan, Dhankuta, Jhumka, Duhabi, Tarahara, and Itahari.
The zone comprised six districts:
| District | Headquarters |
|---|---|
| Bhojpur | Bhojpur |
| Dhankuta | Dhankuta |
| Morang | Biratnagar |
| Sankhuwasabha | Khandbari |
| Sunsari | Inaruwa |
| Tehrathum | Myanglung |
Following the 2015 constitutional reform, these districts became part of Province No. 1 (now Koshi Province).
Etymology / Origin
The name “Kosi” derives from the Koshi (Koshi) River system, the largest trans‑Himalayan river basin in Nepal. The zone was named after the river because its major waterways—including the Arun, Tamor, and the combined Sapta Koshi—flow through the area.
Characteristics
Geography – Kosi Zone spanned a varied landscape, from the Terai lowlands in the south (Sunsari and Morang districts) to the hilly terrain of the mid‑range (Dhankuta, Tehrathum, Bhojpur) and the mountainous regions of the northern districts (Sankhuwasabha). The region’s climate ranged from subtropical in the Terai to temperate in the hills and alpine in the high mountains.
Hydrology – The zone was defined by the Koshi River system. The Arun, Tamor, and Sapta Koshi rivers provided essential water resources for agriculture, hydro‑electric power, and transport. The Koshi Barrage, a major irrigation and flood‑control structure, lies within the former zone.
Economy – The Terai districts, especially Morang and Sunsari, were agricultural hubs producing rice, wheat, maize, and sugarcane. Biratnagar emerged as an industrial centre, hosting textile mills, jute factories, and a growing service sector. The hilly districts contributed timber, horticulture, and tourism, with attractions such as the Tamor River valley and the Hile forest reserve.
Culture and Heritage – Kosi Zone hosted numerous Hindu temples and cultural sites, including the Pindeswari Temple (Dharan), Budha Subba Temple (Dharan), Barahkshetra Temple (Barahachhetra), and the Ramdhuni Mandir (Ramdhuni). The region is ethnically diverse, with communities speaking Nepali, Maithili, Limbu, Newari, and various indigenous languages.
Related Topics
- Development Regions of Nepal (former Eastern Development Region)
- List of zones of Nepal (former)
- Koshi Province (Province No. 1) – the successor administrative unit
- Koshi River basin
- Mahendra Highway – major east‑west roadway traversing the zone
- Biratnagar Industrial District
Sources: Wikipedia entry “Kosi Zone” (accessed April 2026).