Now, lingua franca literally means language of the Franks, which at the time of its creation, really referred to all Western Europeans, not just the people who live in what is now France.
现在, lingua franca 的字面意思法兰克人的语言,在它诞的时候, 实际上指的所有西欧人,而不仅仅在现在法国境内的人。
So Charlemagne, the German Frankish king, has conquered all of Western Europe now comes down to Rome and gets crowned as the Roman Emperor, which is a significant event.
That entity turned out to be a people, another one of those people the Romans would have called barbarians, a people known as the Franks, located in the modern day area of sort of France.