In the Rigveda the term Dasas and Dasyus refers to

The Rigveda contains accounts of conflicts between the Aryas and the Dasas and Dasyus. It describes Dasas and Dasyus as people who do not perform sacrifices (akratu) or obey the commandments of gods (avrata). Their speech is described as mridhra which could variously mean soft, uncouth, hostile, scornful or abusive. Other adjectives which describe their physical appearance are subject to many interpretations. However, some modern scholars such as Asko Parpola connect the Dasas and Dasyus to Iranian tribes Dahae and Dahyu and believe that Dasas and Dasyus were early Indo-Aryan immigrants who arrived into the subcontinent before the Vedic Aryans.