Hmmm
The Roman Empire lasted from 27 BC–476 AD (Western Rome) and 330 AD –1453 AD (Eastern Rome), had a population of about 144,800,000 between Eastern and Western Rome at it's peak.
The Mongol Empire lasted from 1206 AD – 1368 AD.
Wikipedia doesn't have info on their population at first glance so, I'm going to go with 0 or at most the amount of people it took to draw the maps and paint/pose for portraits.
I'm gonna have to go with the Roman Empire on this one.
They gave Western Civilization and Culture so many things, it makes my head pop with the influx of knowledge!