Well, Greateast like ( Large ) or greateast like ( Prestige ). Empire is a false word for a lot of political institution, ( Japan, an empire ? ...) technically Mongols had a very large territory on control, but they were nomadics at the same time and when Gengis Khan died, they go back in central asia and create different and semi-indepedant Khaganat. They were very decentralisated so i dont think we can really call Empire, with peoples with an imperium of all lands that the mongols influence had on control. I think the british commonwealth is a bad exemple too for the same reason, of the decentralisation of european colonialisme, very difficult to control all the territory that are vassals ? of the crown at this time. I think Roman empire were the only institution we can clearly appeal Empire. But in our modern day their is a lot of thing that we can call empire... United states have a great cultural imperialism and maybe a lot of economic deal with all the world and if TAFTA is apply one day, it's gonna become worst for us. China also have a lot of economic deal with others countries for agriculture or use of local resources