What was the general term used for the migrant communities indicating that they did not observe the norms of caste society and spoke languages that were not derived from Sanskrit?

Mlechchha

A more general term for these migrant communities was mlechchha, indicating that they did not observe the norms of caste society and spoke languages that were not derived from Sanskrit. Such terms sometimes had a derogatory connotation, but they rarely denoted a distinct religious community of Muslims in opposition to Hindus.