Even today, 30 years after caste discrimination was declared illegal, it persists, unofficially but pervasively. The President, Prime Minister, Chief Justice, army Chief of Staff and opposition party leader are Brahmins. So are most of the highest echelons of government bureaucracy and politicians. Yet the Untouchables make up over 20 per cent of India's 870 million people.
But at last the Untouchables are beginning to assert themselves politically, ending aeons of mute subservience. Led by Kanshi Ram, a balding former explosives-maker in his sixties, his party of outcastes, in coalition with socialists, are sweeping into power in Uttar Pradesh, India's most populous and politically crucial state. 'My goal is social transformation,' said Mr Ram, who lives in spartan quarters in New Delhi and refuses to attend weddings or funerals because, he says, it distracts him from fighting for the oppressed Untouchables.
It has been a gruelling battle. Caste, in some forms, exists among Indian Muslims, Christians, Sikhs and of course Hindus. The sacred Hindu scriptures, the Upanishads, declare: 'Those whose conduct on Earth has given pleasure can hope to enter a pleasant womb, that is the womb of a Brahmin or a woman of the princely class. But those whose conduct on Earth has been foul can expect to enter a foul and stinking womb, that is, the womb of a bitch or a pig or an outcaste.'
Such religious prejudices against the Untouchables - or Dalits, as they call themselves - are difficult to uproot, as Mr Ram and his socialist partner, Mulayam Singh Yadav, will find when they try to reform the state machinery in Lucknow, capital of Uttar Pradesh. A daily, the Pioneer, commented: 'The biggest challenge would be to keep the bureaucracy (dominated by the upper castes) united and to prevent the caste divide from widening further in rural areas . . . which may lead to a sharp exacerbation of social tensions.'
Indeed, clashes have already flared in the neighbouring state of Bihar, where the Chief Minister, Laloo Prasad, who also comes from a lower caste, enraged Brahmins recently by appointing several Untouchables as priests. In many rural areas Untouchables are banned from even entering a Hindu shrine, never mind conducting the rites. In Bihar many worried upper-caste landlords have formed private armies for defence against what they view as the inevitable uprising of the downtrodden castes.
Success by the socialist-outcaste coalition in Uttar Pradesh and their strong showing in the Madhya Pradesh state elections could signal a major upheaval in Indian politics. Hardest hit is the right-wing Bharatiya Janata Party (BJP), the leading opposition party, which had tried to rally Hindus, who make up the vast majority of Indians, to their banner of religious extremism. Mr Ram showed that the support for Hindu nationalism never trickled down beyond the Brahmins, Kshatriyas and merchant classes. Social justice was a stronger lure for India's downtrodden than the BJP's attempts to reforge a rigid Hindu hierarchy.
The Congress party, whose towering presence has overshadowed India since independence and which now rules in New Delhi, is also shaken by the rising power of the lower castes. Romela Thapar, a historian, said: 'Congress has always counted on the poor, the Muslims and the backward castes to win in Uttar Pradesh and Bihar but they've lost that base now.'