They have taken to the streets to protest against a Supreme Court order that they say weakens a law designed to protect lower caste communities.
Train services have been affected and some highways blocked in a number of states where protests turned violent.
The federal government has asked the court to review its decision.
In its ruling, the court had said that the Scheduled Caste and Scheduled Tribe (Prevention of Atrocities) Act, popularly known as the SC/ST Act, had been "misused" in the past.
Caste violence continues to be a problem in the country. More than 40,000 crimes against lower castes were reported in 2016 alone, according to official statistics.
Dalit leaders said the ruling made them feel "vulnerable".
"The SC/ST Act ensured the protection of Dalits in India by making any discrimination against our community a punishable offence. With this new Supreme Court order, these legal obligations have ended. We're all sad and shocked," said KP Choudhary, the general secretary of an all India association for lower castes.
BBC
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