You need to brush up on your history.
The Chinese Empire lasted for thousands of years and, at it's peak controlled more people and land then did Rome. Certainly in the invention area it dominated the world.
While the Egyptian Empire was not as large it also lasted for over a thousand years and certainly did dominate culturally.
The Roman Empire does not even make the top ten of empires that dominated the world.
It is just the one that we tend to study the most.
Our world is the result of European achievement. It matters little what "empire" ruled more land/people or the longest; it's about today and tomorrow.
I do appreciate the dialog, your reasoning behind selecting paper as most important is the same reasoning for my candidate.