The British Isles were originally held primarily by the Iceni, Gallic, and Celtic people; however, they were conquered by the Roman Empire in 44 BCE. During and after the fall of the Roman Empire, the British Isles were conquered by various Germanic tribes, most notably the Angles, the Saxons, and the Jutes. English people are often called Anglo-Saxon to this day.

Charlemagne is the most famous and most successful (in terms of military conquests) of all the Frankish kings. At the height of his empire in the year 800 CE, he controlled all of modern-day France, and much of modern-day Spain, Italy, Germany, Austria, and the Low Countries. Because he was a powerful and devout Christian ruler, he was invited to become the first "Emperor of the Romans" in a few hundred years, an invitation he gleefully accepted.

The Frankish Kingdom arose in the sixth century in an area that comprises most of modern-day France and the Low Countries. It was built on the conquest of Clovis, who converted to Christianity having won a major battle; however, in Frankish culture, the territory of a ruler is divided between his sons, so the Frankish Kingdom continued to fracture and be reformed through conquest for the next few hundred years.