[Advaita-l] A doubt about Sandhyavandana mantras

[Murali S]

The following mantras are part of Yajurveda Sandhyavandanam(per tamizh
naadu tradition) in prokshanam/marjanam/upasthaanam etc

Aaophistah,Suryashca Mamunyashca,Aapah Punanthu
Prithvim,Dhadhikravinnoh Akaarsham,Mitrasya Charshanni,Asatyena
Rajasa,Imam Me Varuna ,Adhyano Deva Savitaha etc

Are all these mantra-s from the Krishna Yajur Vedam ? If so then do
Rigvedis use equivalent mantras from Rigveda(with similar meaning) for
their sandhyavandanam?

May be irrelevant to this forum,but will thankful to useful pointers.

'People say' that Rigvda is associated with Sindhu-Saraswathi and
Yajurveda is associated with Gangetic regions.Is there truth in that
assertion?