Tyaga
Na Asat
He says part of it was composed out of India. The later books (scholars say books 1, 9, and 10) might have been composed in India. Since RigVeda is not chronologically arranged, it is not possible to know when a particular 'richa' was written. As you know, we have only a small part of RigVeda, a major portion has not survived.
Namaste,
AFAIK there is nothing in RV about such migration from the steppes to Punjab-Haryana region.
RV 6.61.12(from one of the earliest Mandala) states the five Vedic tribes dwelled near the banks of Sarasvati.And RV 7.96.2(again from one of the family Mandala) also suggests that the Purus(perhaps the most important Vedic tribe) also lived near the Sarasvati.Sarasvati river is identified with Ghaggar-Hakra which flows through Haryana.So it is safe to say that early parts of RV was composed in Haryana and not in steppes.
And yes,certain Vedic shakhas might have been lost,but even the current available vast corpus of Vedic scriptures have nothing on steppe homeland.
Even the Gandhara region only appears twice in the entire Chaturvedas,and it doesn't have much importance.All the importance is given to Punjab-Haryana region.