Mleccha (from Vedic Sanskrit म्लेच्छ , meaning "non-Aryan, barbarian") was a derogatory term for people who did not conform with conventional Vedic beliefs and practices.
The term is not attested in the Vedas, but occurs for the first time in the late Vedic text Satapathabrahmana.
By its structure, the term is not natively Indo-Iranian, so that it would seem to be a loan of the self-designation of a non-Aryan people so described, possibly Proto-Dravidian. It has been speculated that the term is related to Meluhha, the name of a trading partner of Bronze Age Sumer, tentatively identified with the Indus Valley civilization.