Kirat or Kirati are indigenous ethnic groups of the Himalayas (mid-hills) extending eastward from Nepal into India, Burma and beyond. They migrated to their present locations via Assam, Burma, Tibet and Yunnan in ancient times. Prototype Tibeto-Burmans originated in the Yellow River basin around 10,000 years ago.
Although only the Sunuwar(the people who inhabit the region westward of River Sun Koshi),Khumbu or Khambu (also known as Rai),Limbu (also known as Yakthumba or Subba) and Yakha (also known as Dewan or Zimdar) are generally called Kirati, the vast majority of ethnic people of the region eastward of Nepal too call themselves as Kirati. These people are also best known as modern Gurkhas. Their languages belong to the Tibeto-Burman family of languages.
The original inhabitants of the Dooars region of India, i.e., the Koch and Mech, also claim themselves to be Kiratis and so do the Bodo and Kachari tribes of Assam.. They derive their titles from the original place of their dwelling, i.e., Koch from the Kosi River, Mech from the Mechi River and the word Kachari is derived from Kachar which means river basin. The basis of these claims relies on the fact that they areMongoloids even though they distinguish themselves from Mongolians elsewhere. They are therefore often identified as Kirati-Mongolians.