A farming culture in the steppes of Russia discovered the war chariot and started expanding in all directions, spreading westwards to Europe and eastwards to India, where they arrived around 1500 BC.
This migration has been traced by historians by studying the changes in language over time. Its turns out that languages as diverse as Indian sanskrit, Persian, Greek and English share a common root. For instance, the Indian word for demon is 'asura', which is related to the Avestan (Persian) word for god 'ahura'. The Indian word for god is 'deva', while the Avestan word for demon is 'daeva'. In this way, many words are linked.
Gods in this area are also similar. The strongest comparison is between Indra (from India), Zeus (from Greece) and Thor (from Scandinavia). All are warrior gods, that live in the sky and wield of the thunderbolt. They are also in king of the gods.
"The Great World History Book"