Scientists have found the earliest recorded usage of a zero, marking a historical turning point in mathematics and society. The Bodleian Libraries at Oxford University announced the discovery from an ancient Indian mathematical document called the Bakhshali manuscript, which was discovered in the late 1800s in what is now Pakistan but has recently been reanalyzed. The text, which is littered with zeroes, has been dated to between 200 and 400 BCE, placing it about 500 years earlier than the next known use of the mathematical symbol. "This isn't some sort of theoretical text, it seems to be a practical document that is being used by merchants to do calculations," mathematics professor Marcus du Sautoy said in a video from Oxford. Those calculations, which include dots that are supposed to be zeroes, were made on dozens of birch bark leaves.