Franks were divided into groups that were led by nobles. Charlemagne united them all and because of this he was crowned by the Pope to be the emperor of everyone. He had nothing to do with Turks or Mongols but he was crowned the Holy Roman Emperor even though he had nothing to do with ancient Roman empire.
Both the U.S. and the Soviet Union build thousands of nuclear weapons during the Cold War. Many of these weapons are many times as powerful as the atomic bombs that the U.S. launched on Hiroshima and Nagasaki.