Varna was a hierarchical social order in ancient India, based on the Vedas. Since the Vedic corpus constitute the earliest literary source, it came to be seen as the origin of caste society. In this Brahmanical view of caste, varnas were created on a particular occasion and have remained virtually unchanged. In this ordering of society, notions of purity and pollution were central, and activities were delineated in this context. Varna divides the society into four groups ordered in a hierarchy; beyond these, outside the system, lies a fifth group known as the untouchables, of which the Chandala became a constituent part.
According to an account, the Adi Sankaracharya met a Chandala in Varanasi, with his dogs by his side.A disciple of Sankara asked Chandala to stand aside. The Chandala reponded "O guru! You preach Advaita Vedanta and yet you make a distinction between man and man. Is Advaita only preached and not practised? Sankara was surprised to hear the Chandala.
In modern Indian usage, Chandal is a general derogatory slur used to refer to a filthy, mean or low person.