Dalits in Bihar are a social group composed of many Scheduled Castes, placed at the bottom of the "caste-based social order". The Dalits also include some of the erstwhile untouchable castes, who suffered various forms of oppression in the feudal-agrarian society of Bihar. Some of the Dalit castes have specific cultural practices, which differ from those of orthodox Hinduism.
In the post-independence period, the failure of land reform led to a lack of socio-economic mobility among them, in contrast to the agricultural castes. This led to an increase in caste-based strife between the Dalit supported Naxalite groups and the state authorities backed by the dominant social groups. In the meantime, many caste-based private armies were formed by the landlord class to quell the Dalit assertion under the banner of Maoism. Ranvir Sena was the most dreaded caste-based militia of the landlords, and perpetrated a number of massacres against the Dalits. Some of the backward castes also emerged as landlords, due to the partial success of the Green Revolution and land reform, and Dalits came into conflict with them as well. In the later years, a socio-political assertion was witnessed in the Dalits of Bihar. After the 1990s, many welfare drives were undertaken by the Government of Bihar to improve the condition of Dalits.