Robert Kaplan, author of The Nothing That Is: A Natural History of Zero, provides this answer:
The first evidence we have of zero is from the Sumerian culture in Mesopotamia, some 5,000 years ago. There a slanted double wedge was inserted between cuneiform symbols for numbers, written positionally, to indicate the absence of a number in a place (as we would write 102, the '0' indicating no digit in the tens column).
The symbol changed over time as positional notation, for which zero was crucial, made its way to the Babylonian empire and from there to India, via the Greeks (in whose own culture zero made a late and only occasional appearance; the Romans had no trace of it at all). Arab merchants brought the zero they found in India to the West, and after many adventures and much opposition, the symbol we use took hold and the concept flourished, as zero took on much more than a positional meaning and has played a crucial role in our mathematizing of the world.
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The mathematical zero and the philosophical notion of nothingness are related but aren't the same. Nothingness plays a central role very early on in Indian thought (there called "sunya"), and we find speculation in virtually all cosmogonical myths about what must have preceded the world's creation. So in the Bible's book of Genesis (1:2): "And the earth was without form, and void."
But our inability to conceive of such a void is well caught in the book of Job, who cannot reply when God asks of him (Job 38:4): "Where wast thou when I laid the foundations of the earth? Declare, if thou hast understanding." Our own era's physical theories about the Big Bang cannot quite reach back to an ultimate beginning from nothing¿although in mathematics we can generate all numbers from the empty set. Nothingness as the state out of which alone we can freely make our own natures lies at the heart of existentialism, which flourished in the mid-20th century.
