After his death, over the course of the 9th century, his empire is broken up. His successors are not able to carry on that title. But then we get into the 10th century. As you can see here, the empire of Charlemagne has now broken up. The west, West Francia, starting to resemble modern-day France, not quite exactly. And the eastern 2 3rds are now under the control of Otto, a German king. And because of his ability to offer protection and frankly, just his power, he is crowned Holy Roman Emperor.