Founded in 1861, with the publication of Hemendranath
Tagore's Brahmo Anusthan" (or
Brahmo Code of doctrine and
practice), Adi Dharm now refers to the religion of
Adi Brahmo Samaj (the first development of
Brahmoism ) and includes also those Sadharan
Brahmo Samajists who were reintegrated into Brahmoism in
1878.
Adi Dharm was the first
organised casteless movement in British
India and reverberated from its heart of Bengal to East Assam, West
Bombay State (modern Sindh, Maharastra and Gujarat), North Punjab and
South Madras, Hyderabad, Bangalore.
Adi Dharm was not conceived as an "anti-caste"
movement, but
stood for repudiation of all "distinctions between people" and
foundation of a modern educated secular Indian nation under the
Eternal, Immutable and Unsearchable Being, and its adherents as
Adi-Dharmis (or worshippers of the ancient formless indivisible One God
Brahman - the Parambrahma "The One without a Second" or EkAdavaitam).
Although the doctrine of Adi Dharma is superficially similar to other
reformatory "sects" of Hinduism which speak of "different paths to One
God", the core beliefs of Adi Dharm irrevocably place Adi Dharm and
Brahmoism as the youngest of India's 9 religions beyond the pale of
"Hinduism's catholicism and elasticity".
The Adi--Dharmis (Brahmo religionists
dispersed throughout India) are distinguished from
Ad-Dharmis (actually a corruption of
A-Dharmis - those with no religion - Sikh and
Christian reconverts by Arya Samaj who formed a Scheduled caste
in North India especially Punjab and Haryana by inspired confusion of
names, doctrines and prophets so as to exploit the legal decision in
1897 of the Punjab High Court which exclusively covered in its scope
Adi-Dharmi Brahmos and the high caste Sikh
"followers" of Brahmoism like Sirdar Doyal
Sing Majithia.) | 
In 1828 Raja Rammohun Roy founded what would come to be known as the Adi Brahmo Samaj |