The term Mleccha is used in Sanskrit often.
There are over fifteen definitions,right from Vedas,Vyakaranas to Amarakosha.
The descriptions vary.
Mlecchas are people who do not follow Vedic life; are uncouth;lack in culture;Speak unintelligibly: Barbarians.
Considering the fact that Bharatavarsha covered more or less the whole world in ancient times,there were only a few countries which were out side Bharata Varsha.
They were called as Mlecchas being outside Vedic Culture.
Some of them were so uncouth,they were called Barbarians.They were not entitled to perform Parvana Sraddha.
Their lands were called Bhoga Bhoomi,land of enjoyment as against Bharatavarsha, which is Karma Bhoomi,where performances rites earn them Punya and Paapa,Good results and Sin.
Some of these lands,Kambhoja embraced Hinduism.
The definition of Milechchcha.
tatra mlecChaan pulindaan ca shuurasenaan tathaiva ca |
prasthaalaan bharataan caiva kuruum ca saha madrakaiH || || 4-43-11
kaa.mboja yavanaan caiva shakaan pattanaani ca |
anviikshya daradaan caiva himavantam vicinvatha || 4-43-12
11, 12. tatra= there – in north; mlecChaan pulindaan ca= Mleccha-s, Pulinda-s – provinces of; tathaiva= like that; shuurasenaan ca= Shurashena, also; prasthaalaan bharataan caiva= Prasthala, Bharata, also, thus; madrakaiH saha = Madraka, along with; kuruum ca= Kuru, also; kaamboja yavanaan caiva= Kaambhoja, Yavana [countries,] also, thus; shakaan pattanaani ca= of Shaka, cities, also; daradaan caiva= Darada, also, thus; anviikshya= on scrutinizing; himavantam vicinvatha= at Himavanta [Himalayas,] search out.
“There in the north, the provinces of Mleccha-s, Pulinda-s, that way Shurashena – Prasthala – Bharata – Kuru – Madraka – Kaambhoja – Yavana shall be scrutinized along with the cities of Shaka and Darada, and then search in Himalayas. [4-43-11,12]
‘The Mleccha is the province of the then India to the North-West and it is defined as: prati anto mleccha sy˜t – amara koþa – go m˜Õsa bhakÿako yastu viruddham bahu bh˜ÿate sarva ˜c˜ra vihŸna× ca mleccha itiu abhidŸyate – bodh˜yana ‘at the end of the country there is Mleccha province…amarakosha, ‘eaters of beef, talkers of odd languages, devoid of all ethics [with reference to Indian scriptural ethics, especially marriage as an institution, immoralities etc.,] and they are called Mleccha-s…’ Bodhaayana aphorisms….,’
Definition from other sources.
Dharmaśāstra (religious law)
Vyākaraṇa (Sanskrit grammar)
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