Regarding the question of when Dravidians reached India,
Bernard Sergent has an answer:
In Indology@... archives, Dr. L. M. Fosse wrote
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The latest theory I have seen concerning this matter is given
by Bernard Sergent in his recent book "Genèse de l'Inde". On
the basis of physical anthropological material as well as
cultural and linguistic, he claims that the Dravidians migrated
from Africa and ended up in India after a stay in the Mediterranean
area. The alleged similarities between Dravidians and Uralian
languages is supposed to have come about through the mechanisms of
area linguistics, indicating that at least some Dravidians and
some Uralians lived in the same area for long enough to influence
each other's language. Incidentally, Sergent does not believe that
the Harappans were Dravidians - that is, except for the population
in the south of the IVC area. Again, his reasons are anthropological.
(He does not suppose that the IVC culture was monolingual).
The Dravidians are supposed to have reached India before the 8th
millennium.
BTW: anthropologically they are Mediterranean, and therefore what we
might term black whites.
>>
Note that most scholars proposing the Dravidian entry
into India dates, do not know not only any Drav. language,
and definitely not the oldest dravidian texts, the sangam texts.
For analyses of Dravidian being the high Harappan language,
refer to Asko Parpola, Deciphering the Indus script, CambridgeUP,
1994, and esp. his articles after 1994.
See also the interview by Iravatham Mahadevan who cracked the
code for reading the earliest Tamil inscriptions from 2nd century BC
available in Sri Lanka and S. India.
One point to be considered in Dravidian language family's
antiquity is drav. relations with any other language family
is so remote pointing to the remote times when it has reached
India.
Munda languages of the eastern India are tribal languages
who have no writing. No texts prior to 100 years! And they
have close relatives in South East Asia. Vedic is related heavily
with old Iranian. But none for Dravidian.
Retroflexion is strongest in the South, and linguists point
to the systemic retroflexion in Indian languages being originating
in dravidian.
Regards,
N. Ganesan