The regiment was raised on 15 June 1941 in Shillong by Lt. Col. Ross Howman to meet the claim of the then undivided state of Assam for its own fighting unit and to counter the threat of the Japanese invasion of India. The area of Elephant Falls in Shillong was chosen to raise the first battalion and it was there, under British instructors, that the first troops were trained. The initial draft of the regiment was drawn from undivided Assam, and consisted of the doughty Tribes of Assam of assam who had proved their martial prowess by defeating the Mughals at the Battle of Saraighat, and tough and cheerful Nagas,Koch-Rajbangshi, Gorkhas, Mizos, Kukis, Khasi, karbi , Garos, Meiteis and other tribals. Later, the Adis, Nishis, Monpas, other tribes of Arunachal Pradesh, northeast India domiciled Gorkhas and Sikkimese and Chhetris were also drafted into the regiment and, today, the regiment can boast of being composed of troops of diverse customs, cultures, languages, traditions and ethos belonging to the seven states of the northeast and Sikkim.