Zain and Swetz in Scientific American:
Sūnya, nulla, ṣifr, zevero, zip and zilch are among the many names of the mathematical concept of nothingness. Historians, journalists and others have variously identified the symbol’s birthplace as the Andes mountains of South America, the flood plains of the Tigris and Euphrates Rivers, the surface of a calculating board in the Tang dynasty of China, a cast iron column and temple inscriptions in India, and most recently, a stone epigraphic inscription found in Cambodia.
The tracing of zero’s heritage has been elusive. For a country to be able to claim the number’s origin would provide a sense of ownership and determine a source of great nationalistic pride.
Throughout the 20th century, this ownership rested in India. That’s where an inscription was discovered, holding the number “0” in reference to land measurement inside a temple in the central Indian city of Gwalior. In 1883 the renowned German Indologist and philologist, Eugen Julius Theodor Hultzsch copied and translated the inscription into English, dating the text to the year C.E. 876. And this has been accepted as the oldest known date for the appearance of zero. However, a series of stones in what is now Sumatra, casts India’s ownership of nothingness in doubt, and several investigators agree that the first reference of zero was likely on a set of stones found on the island.
More here.