The story is a Jack Kirby-like (in particular his ancient astronaut series The Eternals) take on ancient Indian tales, for example the Vedas (a vimana as a flying plane, for example) and Mahabharata.
Morrison has said that the idea arose after 9-11 when his research into Islam led him on to the ancient epic tales of India and some of the more speculative theories of people like David Hatcher Childress.