The ancient Babylonians (preceded by the Akkadians and Sumerians) had a base-60 number system, without a zero. So already 4,000 years ago, people in ancient Babylon understood that it is efficient to make numbers become “circular” or dial-like, in the sense that 60 was like our 10, and 3600 (60 squared) was like our 100, and so on. But the Babylonians didn’t use a place-holding zero, so there were serious ambiguities in their system.

Our number system is far superior to the old Babylonian base-60 system, because our base is much smaller and because we use a zero, and it is also superior to the 3,000-year-old Greco-Roman-Etruscan letter-based system. Zero is the incredible invention that made our number system so efficient. This system was popularized in Europe after the publication, in 1202, of the book Liber Abaci (The Book of the Abacus), by Fibonacci (of the famous Fibonacci sequence). Presumably, Fibonacci learned the use of the 10 numerals with zero from Arab traders, with whom he dealt on behalf of his merchant father, and that is why we often call them the Arabic numerals. But Fibonacci himself refers to them in his book as the “nine Indian numerals” with zero, which he calls zephirum, perhaps originating from the Arab sefir.

The Original Zero
But who invented the zero, which gives so much power to our number system? We don’t know who invented it, but we are pretty sure that the zero is an Eastern invention. The oldest zero in India with a confirmed date is from the mid-9th century, and found in the Chatur-bhuj Temple in the city of Gwaalior.

At one point, an older zero was also known. In the 1930s a zero from the year 683 AD was found in Cambodia, and its great antiquity allowed a French researcher by the name of Georges Coedes to prove that the zero is of Eastern provenance. This is because, while the Gwaalior zero is concurrent with the Arab empire based in Baghdaad (the Caliphate), the zero from 683 predates extensively Arab trading. It also comes from a location that is much farther east than India. Its existence thus makes it highly unlikely that the zero was invented in Europe or Arabia and traveled east through Arab traders, as some had believed in the early 20th century. The Cambodian zero proved that zero was an Eastern invention. But this zero disappeared during the Khmer Rouge regime in Cambodia, and no one knew if it still existed.

The location where the oldest zero in the world, on a 7th century stone inscription, was kept was plundered by the Khmer Rouge as late as 1990, not far from the famous Angkor Wat temple, and after weeks of searching among thousands of artifacts, many of them damaged or discarded, it was able to be discovered from the inscription.

It is the only picture (with a few others my wife took) that exists of this priceless find. Coedes had used only a pencil-rubbing, and never had a photograph. The dot in the center, to the right of the inverted-9-looking sign (which is 6 in Old Khmer) is the oldest zero ever discovered. His Excellency Hab Touch has promised me to bring K-127 back to the Cambodian National Museum in Phnom Penh, where it belongs, and where, hopefully, everyone would soon be able to see it."

References:
Cœdès, Georges, "A propos de l'origine des chiffres arabes," Bulletin of the School of Oriental Studies, University of London, Vol. 6, No. 2, 1931, pp. 323-328. Diller, Anthony, "New Zeros and Old Khmer," The Mon-Khmer Studies Journal, Vol. 25, 1996, pp. 125-132.

Ifrah, Georges. The Universal History of Numbers. New York: Wiley, 2000.
See: http://www.huffingtonpost.com/amir-aczel/worlds-first-zero_b_3276709.html
The zero is the dot in the middle, to the right of the spiral-looking character, which is a 6 in Old Khmer. The numeral to the right of the dot is a 5, making the full number 605. The inscription says: “The Shak era reached year 605 on the 5th day of the waning moon…” We know that in Cambodia the Shak era began in the year 78 AD. Thus the date of this zero is 605 + 78 = 683 AD.

Some Other Views-Read them, They Might Help
Aaryabhat, who while never used the symbol for zero because he did not use the Indian numerals, had already used a placeholder (a dot) for powers of 10. Thus, he was aware of the concept of zero. And this is between 476-550 AD, clearly predating the Cambodian zero.

The use of zero is basic to the Maayaa Base-20 system of positional numeration. Amit Acad should have done more research. This is a misleading article and I'm amazed that Discovery magazine published such a claim. The Khmer of Cambodia were pretty amazing, but the Maayaa mathematicians have priority.

The Maayan zero is a place-holder as well, as a simple search of "maya and zero" quickly shows.

The Maayaa zero was used in calendar works to denote zero days or years, etc. It was different from our versatile, multi-purpose, base-10 "Hindu-Arabic" system of calculation. For the Maayaa zero and its purposes, see Georges Ifrah, "The Universal History of Numbers", NY: Wiley, 2000, pp. 316-322.

The earliest known use of zero in Meso-America is in 37 BC. Zero is used not only in the long count calendar but also as a placeholder in their modified vigesimal counting system. The Olmec and Maayans had advanced mathematics for calculating astronomical events and positions of which could not have been calculated without a value assigned to their zero. - Haughton, p. 153. The earliest recovered Long Count dated is from Monument 1 in the Maayaa site El Baúl, Guatemala, bearing a date of 37 BC.

The Maayan 10 is a =, not one and zero next to it; and after 19 you get to powers of 20 -- zero is not used in that notation; the zero glyph is very different. The Cambodian zero is a place-holder, just as in our "Hindu- Arabic" numerals.

Why call the Hindu numerals as "Arabic"? Algebra too was invented by the Hindu, but that is not being called the Arabic term - Al Gebra, enough?

The earliest known use of zero in Meso-America is in 37 BC. Zero is used not only in the long count calendar but also as a placeholder in their modified vigesimal counting system. The Olmec and Maayans had advanced mathematics for calculating astronomical events and positions of which could not have been calculated without a value assigned to their zero. As an example, the decimal value of 361 is represented by three Maayan glyphs the first and third being single dot like our period "." and the second or middle glyph would be a modified "turtle shell" representing zero (0) - such as --
.0 . = 1 x 360
0 = 0 x 20 . = 1 x 1
For a sum of 361.

I don't know what a "modified" ; base 20 system looks like, but if extend hexadecimal (base 16) with g=16, h=17, i=18, j=19, 361 ((18*20 +1) is represented as i1, no need for a "zero", 401 (1*20^2 + 1), on the other hand is 101 in base 20. Why otherwise in base 20 any number less than 400 base 10, needs 3 digits?

There are two number systems the Mayan use. Both are placeholder value systems using base-20 or a modified base-20.
For arithmetic, they used a straight base-20 system throughout with a zero placeholder. This was done through a series of horizontal bars and dots stacked upon one another for values greater than zero and a "shell" of sorts for a placeholder of zero. Their second counting system was for the long-count calendar. This was a modified base-20 system whereas the third digit was base-18 and all the others were base-20.

Maayan civilization peaked between 300 - 800 AD. The first three centuries of this period corresponded to the Gupta age in India (300- 600). It's pretty amazing that 2 civilizations on opposite sides of the world both invented the symbol for zero at roughly the same time. The predictable part is that once it was invented in India, the zero symbol spread east and west quite rapidly. In contrast, in the Americas, Maayan hieroglyphs (and the zero) remained confined to Meso-America - due in large part to the north-south axis of these continents.

Well, we all might argue the origin of the universal 0, but what's important is how the 0, the nothing became everything in modern communications. It is because the 0 is the intangible that creates the tangible through Baby Bangs occurring at the instantaneous speed of Time, where the past collides with the future, manifesting The Eternal Now (T.E.N. 010) that just past, gone into the unknown oblivion, not to be repeated (exactly) ever again. Go Baby Bangs vs. the elusive Big Bang. The universe is dualistic in term of 010, as the concise equation for the unified field theory, or, the Theory Of Everything, for the next billion years.