It is popular in Himalayan Tarai of Nepal i.e., Kapilvastu, and eastern Uttar Pradesh, where it is known as the scented black pearl.
It was featured in the book Speciality rices of the world by Food and Agriculture Organization of the United Nations.
Acreage under this variety has declined sharply, pushing it towards extinction, for reasons including: Kalanamak was grown widely in Kapilvastu and UP's Tarai belt, which comprised districts Siddharth Nagar, Sant Kabir Nagar, Maharajganj, Basti, Gonda, and Gorakhpur.
Kapilvastu, part of the Kingdom of King Śuddhodana, father of Gautama Buddha is located in Terai, Nepal.
Chinese monk Fa-hain wrote that when Buddha visited Kapilvastu for the first time after attaining 'enlightenment', he was stopped at Mathla village by the people.
[citation needed] The first effort to conserve Kalanamak rice was made by Englishmen William Pepe, J H Hemprey, and Edcan Walker (Jamindars of Alidapur, Birdpur, and Mohana) during the British Raj.
They produced this variety for their consumption and transported it to England from Uska-bazar mandi, passing through Dhaka (now in Bangladesh).
Due to increasing demand, the British captured the land around Kapilvastu and established Birdpur and Alidapur states.
The government of India came out with its Nutri-Farm scheme in 2013, intending to promote food crops that offer critical micronutrients to improve the nutrition status of the vulnerable section of society.
In recent years, several government bodies, agricultural organizations, and NGOs have taken steps to revive Kalanamak rice: