The concept for zero might seem obvious to you, but that's probably just because you're accustomed to it. It's actually a deeply sophisticated notion, one that scientists didn't believe we had an established symbol for until sometime between the 9th and 12th centuries. Now, however, that date could get pushed back by 500 years, thanks to a new analysis of an ancient Indian document known as the Bakhshali manuscript, reports Gizmodo.

The Bakhshali manuscript — written in a Buddhist Hybrid Sanskrit — is littered with a symbol for zero, conveyed by a solid black dot, but scientists have long assumed that the document dated to some time between the 8th and 12th centuries. But those assumptions were based on things like the style of writing, or the literary and mathematical content, not on a firm carbon date.

It wasn't until this year that researchers from the University of Oxford's Bodleian Libraries and the Oxford Radiocarbon Accelerator Unit finally collaborated on a project to officially carbon date the document. To everyone's surprise, it dated to between 224 to 383 AD, much older than the earlier analysis suggested.

This is significant for several reasons. First, it's the black dot depicted in the Bakhshali manuscript that would later evolve into the hollowed out circle we're all familiar with that designates zero today. Second, although this black dot did not yet represent zero as a full blown number in its own right, this is the only known example of a zero symbol that did eventually become that.

"The zero used in the Bakhshali manuscript is not yet a number in its own right. It is a place holder being used as part of another number written in the place number system," explained Marcus du Sautoy, an Oxford University Professor of Mathematics. "We write 101 to indicate 1 hundred, no tens and 1 unit. The zero is indicating the absence of 10s."

This isn't unique to the Bakhshali manuscript — a practice of using zero as a placeholder can be independently traced to cultures as far-reaching as the Babylonians and the Mayans — but it's the symbol depicted in the Bakhshali manuscript that eventually crossed the threshold into full-blown numberhood. That makes this find of particular historical importance. This was the linchpin when it comes to zero being thought of as a number.

Once zero was thought of as a number, it allowed the first use of negative numbers and decimal fractions. Zero allowed for the consideration of maths as a concept as opposed to simply a counting system for tangible or quasi-tangible problems.

"Determining the date of the Bakhshali manuscript is of vital importance to the history of mathematics and the study of early South Asian culture and these surprising research results testify to the subcontinent's rich and longstanding scientific tradition," noted Richard Ovenden, a Bodley Librarian, in a statement.