What is "bundahishn"

Bundahishn , meaning "Primal Creation", is the name traditionally given to an encyclopædiaic collections of Zoroastrian cosmogony and cosmology written in Book Pahlavi. The original name of the work is not known.

Although the Bundahishn draws on the Avesta and develops ideas alluded to in those texts, it is not itself scripture. The content reflects Zoroastrian scripture, which in turn reflects both ancient Zoroastrian and pre-Zoroastrian beliefs. In some cases, the text alludes to contingencies of post-7th century Islamic Iran, and yet in other cases (e.g. in the idea that the moon is further away than the stars) reiterates scripture even though science had by then determined otherwise.