Derivation of word "Hindu"

[jacob.baltuch at euronet.be]

>        The ancient Iranians presumably did not have the sound-changes of
>historical philology in their heads. So when they heard of the river
>called Sindhu, why did they call it _hindu_ and not, say, *_sindu_ (since
>Avestan and other ancient Iranian languages do have initial s, cognate
>with the Sanskrit palatal fricative)?
>
>        Thieme, quoted in Mayrhofer's _Kurzgefasstes_, seems to be right
>in taking _hindu_ as a common noun, not as a place-name, whether or not
>he is right in interpreting it as 'the frontier'. It would then be
>understandable that they should use their own word rather than a foreign
>one of similar but different form.
>
>        Or did the sound change s>h take place after the Iranians had
>settled in Iran and come to know the Indus by the name _sindhu_?

Wait a second, my understanding of (for example) Lars Martin's explanation
was that Iranian hindu was cognate to Indian sindhu, not that it derived
from it, although I can't go back an check.