Upon reading the Mleccha page of Wikipedia there is a section which says:
Later Vedic literature speaks of the western Anava tribes as mlecchas and occupying northern Punjab, Sindh and eastern Rajasthan. The tribes of the north were mlecchas either because they were located on the frontiers such as Gandhara, Kashmira and Kambojas and therefore both their speech and culture had become contaminated and differed from that of Āryāvarta, or else, as in the case of southern India, they were once Aryas but having forsaken the Vedic rituals were regarded to mleccha status.
I know that mleccha refers to "outcasts" and what people perceive as "non-Vedic", but in the vedic era there was no foreign influence of other religion on Kashmir so why was this term used? Or was this term added after the influence of foreign religion in Kashmir?