Keivom was undergoing treatment for multiple health complications since June, family sources said.
He was later diagnosed with cancer and bed-ridden since then, they said.
He breathed his last at Max Super Speciality Hospital in Delhi at 5.46 am, they added.
He is survived by four children, who live abroad.
Keivom was nicknamed "Zoram Khawvel Pa" after his masterpiece "Zoram Khawvel" and for his contribution towards the integration of "Zo hnathlak" — descendants of Chin-Kuki-Mizo-Zomi group.
He was born at Pherzawl, a remote village in Manipur's Churachandpur district (now Pherzawl district), in 1939.
He belonged to the Hmar tribe, one of the major tribes of Chin-Kuki-Mizo-Zomi group.
He graduated from DM College, Imphal in 1963 and obtained a master's degree in History from Gauhati University in 1966.
He joined the Indian Revenue Service (Customs and Excise) in 1967.
He joined the Indian Foreign Service (IFS) in 1970 and was posted in at least six countries, including Italy and New Zealand, during his 32-year-long career as a diplomat.
He retired from his job in 2002.
Keivom did not sit idle after his retirement as his passion and thirst for literature, which he believed was one of the main contributing factors towards the unification of "Zo kindred tribes", made him travel to different places of the Zo tribes and he carved a niche among famous Zo (Mizo) litterateurs.
Keivom has written at least 22 books in Hmar, Mizo and English and composed over 150 songs, including Hmar nationalist songs.
His book "Zoram Khawvel" (eight volumes) won the prestigious 'Book of the Year' award by Mizo Academy of Letters in 1991.
His book "Zoram Khawvel-4" is often compared to Adolf Hitler's 'Mein Kampf' for its insightful and authoritative discourse on Zo nationalism and unification.
He also translated Holy Bible and Rabindranath Tagore's Nobel Prize-winning work Gitanjali to Hmar.
(With Inputs from PTI)
