Kosi Zone

The Kosi Zone (Nepali: कोशी अञ्चल [ˈkoʃi ˈant͡ʃal]) was one of the fourteen zones of Nepal until the restructuring of administrative divisions in 2015. It was located in the Eastern Development Region, encompassing six districts: Bhojpur, Dhankuta, Morang, Sankhuwasabha, Sunsari, and Terhathum. The zone was named after the Kosi River, a major river system that flows through the region. Biratnagar served as the zone's headquarters.

The Kosi Zone spanned diverse geographical regions, from the Himalayan foothills in the north to the fertile plains of the Terai in the south. This resulted in a wide range of climates and ecosystems. Economically, the region was primarily agricultural, with significant industrial activity concentrated in the southern Terai districts, particularly around Biratnagar.

Following the adoption of a new constitution in 2015, Nepal transitioned from zones and districts to provinces. The territory formerly comprising the Kosi Zone is now primarily part of Province No. 1, later renamed Koshi Province in 2023. The historical significance of the Kosi Zone remains relevant for understanding the regional geography and administrative history of Nepal.