A world where the HRE formed around Aachen and the Carolingians. It's much more centralized than the German-centered HRE of our world, with the Emperor holding much more power, an emperor in fact as well as name.
Subsequent events in this world's history include a Magyar immigration to Anatolia, not the Balkans, resulting in their eventual absorption and loss of national identity. The Avars grow into a powerful, centralized nation, as does Asturias. The Vandals survive in North Africa and are eventually converted to Islam. The Viking age concentrates its raids to the east, not willing to brave the power of the CHRE. Their one foray to the British Isles results in an invasion of Mercia by the CHRE.
Migration patterns and national origination is different in this world, as evidenced by a more westerly-oriented Poland.
One other note: the Americas were contacted by Europeans in the 13th century, but never colonized apart from scattered trading posts. As a result, many native American peoples developed strong nations of their own, on par with Europe. One of these, the Hadenosau (our world's Iroquois), is one of the strongest powers in the world, with colonies of its own in Africa and the Pacific.