Kazanas appears to be on fairly sound ground when he argues that the horse sacrifice in a late Ancient Mesopotamian text is due to Vedic influence. A rich horse mythology is attested in almost all Indo-European traditions, the horse sacrifice is referred to in late hymns of the Ṛgveda (RV 1.162 and RV 1.163), and is perhaps alluded to in the early family books (RV 3.53.11), and the peculiarity that in both the Vedic and Ancient Mesopotamian traditions a priest whispers into one of the horse’s ears would seem to indicate that the borrowing is a certainty.
Levitt, S. H. (2012). Vedic-ancient Mesopotamian interconnections and the dating of the Indian tradition. Annals of the Bhandarkar Oriental Research Institute, 93, 137-192. -- surely the original verses from the Rigveda would be more quotable than this
