While many ancient number systems did not employ the symbol “o”, many did employ letter/numeric symbols, grammar symbols & or place markers to designate what we would now designate as “0” in writing numbers.
While the report may represent the oldest written “zero” in a numbers sense, I am not sure it represents the oldest use of zero, the concept or its placeholder in number systems. The symbol “o” and the concept are separate.
That altogether has a whole separate history from the philosophical dialogues about “zero”, and symbols for it meaning as “nothing”.
