The highland district of Longleng is found in the northern region of the Indian state of Nagaland. The Phom Nagas live there. Its headquarters are in the town of Longleng. Natural waterways like the Dikhu river provide as a clear border for the area. Its boundaries are the Tuensang district in the south, the Mokokchung district in the west, the Mon district in the east, and Assam in the north. The highest mountain in the district is Mount Yingnyiüshang, which is located in the southeast and rises to a height of around 2,500 meters above sea level.