havuoksa
Warlord
Yeah, that was my thought. Rome includes England, France, Italy, Spain, Portugal, Greece, Turkey, Croatia, Slovenia, Albania, Algeria, Libya, Tunisia, Morocco, Syria, Lebanon, Israel, Egypt, and a few other countries I'm missing. While Mongolia had a larger empire, those countries don't necessarily have that many medals, with the exception of China.
Another candidate is the Arabs, if you include them at their height to include Spain.
ETA: I forgot about Russia under the Mongols. Yeah, the Mongols probably do win.
But AT THE TIME OF THEIR LEADER (Rome)! So I would't agree Rome would have all those countries you mentioned in Civ5(?). Mongolia at Genghis Khan on the other hand does have those countries mentioned above...