criteria for extra-South Asian origins of concepts and words (was Re: Jamshid)

[Sudalaimuthu Palaniappan]

In a message dated 6/14/99 1:03:19 PM Central Daylight Time, thompson at JLC.NET
writes:

> In any case, one point may be worth the list's attention: the concept of
>  mAyA seems by no means to be a unique development of the South Asian
>  culture area. The Vedic Aryans appear to have brought this idea with them
>  as an inheritance from the common Indo-Iranian period. That at least
>  appears to be suggested by the evidence, as I see it. Likewise for the
>  culture concept mantra, for example, which is as deeply rooted in Avestan
>  as it is in Vedic.

I have a theoretical question. In discussions of Dravidian etymology of
words, a criterion often used to argue for proto-Dravidian origin is whether
cognates occur in non-contiguous branches of Dravidian , eg., cognates
occurring in north and south Dravidian. What are the corresponding criteria
used in the case of IE to conclude proto-IE origins? A related question is
can the occurrence of a concept or a linguistic item in both Iranian and
Indian be used to argue against it first originating in South Asia and
spreading to Iranian, given the proximity of the two? Thanks in advance.

Regards
S. Palaniappan