freinds, three issues are fundamental in understanding tamils background.
1. genetics: recent mitochondrial DNA studies by prof.picchapan and oxford paleo-anthropologist spencer wells have proven that people in south india(and ceylon) are coastal veddoids. that is they are the missing link between the early african emigrants(60,000 years ago)and australian aborigines. the correct anthropological term for these people is" melanids"(the other name proposed was sudroid and was rejected as it has pejorotive connotations).
most of us are a way related closely with these coastal veddoids.the mixing kept happening for the past 10,000 years from now. the unmixed veddoid populations still live in high mountains,forests and coastal fringes of peninsular india.
2.language: the proto-dravidian language came to indian peninsula from sumeria(modern iraq)about 6000 years ago and must have reached present day tamilagam 4000 years ago only. (prior to this here there could have been a austric type of language like munda-presently spoken in jarkhand) the proto-dravidian language on its way matured into several languages like brahui,kondi,malto, telugu and kannadam...etc. but it was most well developed on its way down to the southern tip of the indian peninsula. it was well here preserved due its geographical insulation in tamilagam.
it is possible to speculate that the first sangam was in sumeria and the second sangam was in indus valley. the third and last sangam only was in madurai.
the so called kumari kandam could only have been in africa from where our genetic ancestors came from in order to escape from a famine. or it could be in sumeria from where language ancestors emigrated 6000 years ago. the journey and the mother land are preserved in our collective unconscious as a dream land called kumari kandam!there is no geological possibility of a kumarikandam.
3. religious affiliation and varna: the hindu religion is made up of several streams of thought and philosophies. the nordic aryans who came from volga river basin to turkistan stayed there5000 years ago. their stay is now proved beyond doubt from archeological excavations.
they came with a superior language and assimilated all other existing cults, philosophies and languages into their vast culture.
the meditating man in indus seal is an example of yoga and meditation prior to the vedic hinduism. even now sankhya and yoga are debated to be pre-aryan. jains also feel they have a pre aryan background.
many upanisad chapters have possible resources outside their traditional beginning(iam nable to prove this now)
but every thing is now melted into a single pot called hinduism. there is no way we can divide and show the difference, unless it is too academic a forum.
all have a pre aryan element in our worship. for example worship of anjaneya in northindia. the idols of various animals in south indian temples. these are all the animist elements in our religion which have not faded away.
our present religion has all the three elements. the aboriginal element that is predravidian, the dravidian agama pattern and the vedic hindu pattern.
in chidambaram we have all the three with equal importance. it is for anyone to see the animal images and the dark siva and the aryan gods like indra and soma...etc.
thus a tamilian is not a pure concept. it is part of a larger spectrum of southasia. but it is one end of the spectrum (which makes many people to mistakenly split it and make into water tight compartments like tamil and non-tamil...etc)