A prominent political leader of the lower-caste Dalits in India, Kanshi Ram, has died at his home in the capital, Delhi.
Mr Ram,72, founded the Bahujan Samaj Party, a regional party which he led along with Mayawati, a former chief minister of Uttar Pradesh state.
He was ailing and bedridden for the past two years, reports say.
Mr Ram emerged as the symbol of a growing political role for the Dalits in Indian politics in the 1980s.
In his condolence message, Indian PM Manmohan Singh described Mr Ram as "one of the greatest social reformers of our time...his political ideas and movements had a significant impact on our political evolution".
"He had a larger understanding of social change and was able to unite various underprivileged sections of our society and provide a political platform where their voices would be heard," Mr Singh said.
Under Mr Ram's leadership, the BSP won 14 parliamentary seats in the 1999 federal elections.
The BSP, founded in 1984, has led the government in the restive and politically crucial northern Indian state of Uttar Pradesh several times.
In 1995, Mayawati, who was groomed by Mr Ram, took over and became the first leader of a Dalit party to head a state government in India.
Apart from Uttar Pradesh, the BSP has a considerable presence in Punjab as well as the central state of Madhya Pradesh.
Analysts say Mr Ram was an astute politician and was hugely influential among India's Dalits or untouchables.
Under Mayawati's leadership, the BSP has now toned down its anti-upper-caste rhetoric to broaden its support base, reaching out now to the upper-castes and to Muslims.