You sure about this? I've heard plenty of hearkening back to the Roman Empire, too, especially by historians who specialize in antiquites. Besides, the Carolingian empire was somewhat small for a unified Europe, notably lacking in Spain, the Balkans, and Britain. And even though the treaty of Verdun was not responsible for the cultural differences between France, Germany, and Italy, they still existed, as any comparison of the parts of the late Empire will show.