Zero as a number is only 1,400 years old.
Earlier systems knew zero at most as a placeholder; Roman numerals didn't even have that. In 628, the Indian mathematician Brahmagupta first described rules for zero as a number in its own right in his 'Brahmasphutasiddhanta', for instance that a minus a equals zero. The system reached Europe via Arab scholars; Fibonacci popularised it in 1202 with his 'Liber Abaci'.
Useful: Try multiplying 1,234 by 56 in Roman numerals and you'll know what zero is worth.
Source: en.wikipedia.org