Indra, armed with a thunderbolt, on his mount Airavana, the white elephant with three heads born of the churning of the Sea of Milk.
Indra is attested as a god of the Mitanni. If Indra as a deity is cognate to other Indo-European gods, either thunder gods such as Thor or Perun, or heroic gods, or gods of intoxicating drinks, his name has either not been preserved in any other branch, or else it is itself an Indo-Iranian innovation. Janda (1998:221) suggests that the Proto-Indo-European (or Graeco-Aryan) predecessor of Indra had the epitheta *trigw-welumos "smasher of the enclosure" (of Vritra, Vala) and diye-snūtyos "impeller of streams" (the liberated rivers, corresponding to Vedic apam ajas "agitator of the waters"), which resulted in the Greek gods Triptolemos and Dionysos.
In the religious practices of the foundation of Hinduism, i.e. Vedic civilization, Indra has prominence over the continuation of chief god of the Indo-European pantheon Dyēus (Dyēus appears in the Vedas as Dyaus Pita, a relatively minor deity who, interestingly, is the father of Indra). Compare to this the relatively low status of Tyr compared to Odin or Thor in Norse paganism. The battle between Indra and Vritra is reflected in the Avesta[citation needed], but only among the Indo-Aryans does Indra appear to have risen to the head of the pantheon.
http://en.wikipedia.org/wiki/Indra
