The Limbu (exonym) or Yakthung (endonym) are a Sino-Tibetan indigenous tribe (Bhot-Burmeli) of the Himalayan region of eastern Nepal, Sikkim, and western Bhutan. The original name of the Limbu is Yakthung () or Yakthum. Limbu males are called Yakthungba or Yakthumba and Limbu females are called "Yakthumma" or "Yakthungma". Ancient texts state that "Yakthung" or "Yakthum" is a derivative of Yaksha and some interpret its meaning as the "Yaksha winner". In the Limbu language it means "heroes of the hills" (Yak - hills, thung or thum - heroes or mighty warriors), which connotates with the ancient Kiratis. Subba is a title given by the Shah Kings only to Limbu village chiefs. Subba was not an indigenous Yakthung terminology, but now the two terms are almost interchangeable. People often debate about the use of term "Subba" as their surname in Limbu tribe. It is important to note that only the village chiefs were allowed to use the term Subba in their name. It was how the village chiefs were distinguished from other villagers in Limbu tribe. Family lineage of the village chiefs are often found with their surname as Subba. Their history is said to be written in a book called Bangsawoli (Genealogy), also known as Bansawali. Some ancient families have kept copies. There are hundreds of Limbu clans and tribes, classified under their tribe or subnational entity or according to their place of origin. The Chinese text Po-ou-Yeo-Jing, translated in 308 AD, refers to the Yi-ti-Sai (barbarians bordering on the north), a name which is an exact equivalent of The Limbu were also one of the earliest inhabitants of Sikkim. The name of the Indian state itself is a combination of two Limbu words: su, which means "new", and khyim, which means "palace" or "house". The estimated population of the Limbu is 700,000, mainly in the districts of Sankhuwasabha, Tehrathum, Dhankuta, Taplejung, Morang, Sunsari, Jhapa, Panchthar, and Ilam in Nepal. These are all within the Mechi and Kosi Zones or "Limbuwan". Portions of the Limbu population are also located in the eastern and western districts of Sikkim. A smaller population is scattered throughout the cities of Darjeeling, and Kalimpong in West Bengal, Assam, Nagaland, Bhutan, and Myanmar. Some have migrated to the United Kingdom, Hong Kong, the United States, and other countries. History Language Limbu is one of the few Sino-Tibetan languages of the Central Himalayas that possesses its own