1200 - 900 BC
Composition of the Purusha Sukta, a hymn in the Rigveda, the earliest Sanskrit text and a foundation of the later Hindu tradition. It describes the creation of the world from the sacrifice of a cosmic man, from whose mouth, arms, thighs and feet emerge the four classes, or varnas, of society. This is the first textual representation of a system of social stratification that will later be known as caste.
200 - 100 BC
Early Buddhist literature describes and criticizes the hierarchical, birth-based division of society. The Buddha, in this literature, argues against the divine origin of hierarchy and institutes the sangha, a monastic order into which members of all classes are admitted.
200 BC - 200 AD
Composition of Manu Dharmashastra, a Sanskrit code of laws and norms influential in the later Hindu tradition. Manu elaborates the four-fold structure of society, prescribes privileges and disabilities according to status, and identifies despised groups outside the four varnas – groups that will later be identified with the "untouchables."
Chinese Buddhist traveller Hsuan-tsang journeys through India. His travelogue provides evidence that signature conditions of untouchability – segregation, imposed disabilities and defiling labour – existed at that time.
The Veerashaivas, a radical anti-caste sect led by Basava in Kalyan in South India, briefly attain prominence and face violent suppression.
Beginning of six centuries of rule of large portions of South Asia by Muslim kings – the Delhi Sultans and the Mughals. During this period, the spread of Islam and the cultural influence of generations of immigrants from Arabia, Persia and Central Asia in some ways destabilize and alter aspects of the caste order.
The British East India Company begins to rule increasingly large portions of the Indian subcontinent, and is replaced by the British Crown in 1858. While in certain respects disrupting the caste order, British colonial administration also buttressed the traditional privileges of the brahmins and did little to end the discrimination against "untouchables."
"Low"-caste radical Jyotirao Phule pens Ghulamgiri ( Slavery), a fierce critique of the collusion between brahmins and British administrators, which compares the caste system to American slavery.
The British begin to outlaw some practices of untouchability, and reserve places in local government for the traditionally excluded.
Young Dalit lawyer Bhimrao Ambedkar gathers thousands of "untouchables" to draw water from a public well to which they have been denied access in Mahad, Maharashtra – the first big public action in a lifetime of activism that will reshape India.
Ambedkar pushes the British to create separate electorates for Dalits (as they will for Sikhs and Muslims), but Mohandas Gandhi, with whom he has otherwise been a colleague in the fight for independence, rigidly opposes the idea. Gandhi begins a "fast unto death" to oppose the move, until Ambedkar and his Dalit supporters drop the demand; many Dalits will later feel he set back the cause of ending caste discrimination by decades.
Independent India's new constitution, written principally by Ambedkar, comes into effect. It outlaws discrimination based on caste and the practice of untouchability. It also reserves 22.5 per cent of its educational and civil service seats for "untouchables" and aboriginals.
Ambedkar leads 500,000 Dalits in a mass conversion to Buddhism, the largest religious conversion ever.
A "Dalit Panther" movement is founded in Bombay, modelled on America's Black Panther movement, with the same sort of radical ethos in the push for rights. They claim the name Dalit, which comes from the Sanskrit word meaning "broken" or "oppressed." The movement spurs the emergence of a new Dalit literature.
Mayawati, a Dalit woman, is elected chief minister of Uttar Pradesh, India's most populous state. She heads the Dalit-based Bahujan Samaj Party, founded by a leader named Kanshi Ram, which claims to be continuing the legacy of Ambedkar, and emerges as a powerful new political force in north India.
The World Conference Against Racism in Durban, South Africa, becomes a hotly debated topic in India, with Dalit activists determined that discrimination based on caste be raised at the forum but the government of India manages to keep it off the agenda.
Human-rights organizations collect more than 100,000 reports of atrocities against Dalits in this year alone. They include murders, rapes and arson attacks on Dalit communities. Only a handful of arrests are made.