DesiPundit

According to Romila Thapar, Indo-European speakers had central Asia as their habitat and gradually over many centuries they branched out in search of fresh pastures. According to her, it is these central Asian migrants who wrote the  Avesta in Iran and Rig-Veda in India. According to Thapar there is an argument that people who migrated to India were dissidents of the Old Iranian, hence you find a significant reversal of meaning in concepts common to both Avesta and Rig-Veda.

Varnam, responding to a post on The Acorn, examines the similarities between Avesta and the Rig Vedas.