What is proof to you for something that happened 2500 years ago? Certainly all the external evidence that conincides with the book of Jerimiah confirms it and none contradicts it. This is true with the entire bible. Whatever your standard of proof we have much more evidence (by very large margins) for the veracity of the Bible than we do for whether a gereral named Hannibal ever even existed, much less crossed the alps - Same for a leader named Julius Caesar, particularly his Galic, Spanish and African campaigns. Only a handful of texts have ever been discovered that these things really happend although no scholars really dispute them.
So, tell me, how did this pebble help you figure out exactly which sect to belong to?