Rai people

The Rai are one of Nepal's most ancient indigenous ethnolinguistic groups. They were Raya meaning king. Once someone was recognized as a ruler then Hindus awarded the title Raja, Rai, Raya, Malla etc. When Kirant kings were defeated by Prithibinarayan Shaha then in B.S. 1832 given the title of Rai instead of Raya to all kirant people who used to live in wallo kirant and majh kirant for particular reason. The Rai are the Khambu (people of Khumbu region) The Rai belong to the Kirati group or the Kirat confederation that includes Limbu, Sunuwar, Yakkha and Dhimal ethnic groups.
According to the anthropologist Dor Bahadur Bista of Tribhuvan University and late Professor Suniti Kumar Chatterji (linguist and kiratologist, Calcutta University), Kirats migrated from the east via north Burma and Assam along the mid-hills (lower mountains) with their pigs in ancient times. (ref.30,31). Specially it is referring to Limbu and Dhimal who used to call themselves Yakthumba or Yoktumba. According to Imansing Chemjong they migrated from the Assam valley to Pallo kirant in around 600 AD.
According to Chatterji and other prominent linguists, the Rai, Limbu, and Dhimal languages are pronominalised (Austric/Kol influence) strongly indicating earliest migratory wave of these peoples compared to other Tibeto-Burmans whose languages are non-pronominalised. (ref.31)
The traditional homeland of the Rai extends across Solukhumbu, Okhaldhunga (Wallo Kirat or Near Kirat), home of the Nachhiring, Bahing, Wambule subgroups); Khotang, Bhojpur and the Udayapur Districts (Majh Kirat or Central Kirat), home of Bantawa, Chamling, in the northeastern hilly region of Nepal, west of the Arun River in the Sun Kosi River watershed. Rais are also found in significant numbers in the Indian state of Sikkim and in the northern West Bengal towns of Kalimpong and Darjeeling.