Carved out of Tuensang district, Longleng is tenth district of Nagaland. It is bordered by Mon district in the north, Mokokchung district in the west and Tuensang district in the south. The district's headquarter is Longleng, which is at an altitude of about 1,066 m above sea level. Tamlu and Longleng are the major towns in the district. Its main river is Dikhu.