How do you write zero in Roman numerals? Answer: you can't. Even though they used their number system for adding amounts of money, they hadn't figured out "cardinal zero" yet.

It was introduced into western mathematics through Fibonacci in the 1200s at the same time that Hindu-Arabic numerals were adopted, which use "0" as a placeholder (compare this to earlier Greek numerals which work similarly to the system we use today but without placeholders and using different sets of symbols for the different places—and of course no way of representing zero).

That's what I'm talking about (though I guess the "thousand years" estimate was slightly high). Why did it take hundreds of years after the introduction of zero to get "the zeroth element of a sequence", which is quite a new usage, and even now is confined to specialized fields?