There’s no other book quite like Jonah in the Bible. It’s almost completely self-contained without the interference of other writers, historical figures, or references to Israelite history. There’s no date given or historical precedent for why Jonah’s been called by God. What we do know is Jonah is mentioned in 2 Kings 14 during the reign of Jeroboam II which would have been the 8th Century and Assyria gaining power. We know Ninevah was destroyed by Babylon in the 6th Century, so it stands to reason Jonah is somewhere between the two. Regardless, this folklore-style prophecy is one of the most descriptive and peculiar books in all the Bible.