The Babylonians did not destroy Ashurbanipal's library; they carted it home, and what is left at Nineveh is the leftovers.

But they wouldn’t destroy the library because it was the giant brain from which the Assyrians ran a world empire, and it had all the knowledge in the world. They destroyed that? They spoke the same language, they had the same writing system. They’d have taken them all safely home, cart after cart after cart.