After the fall of the roman empire, the merovingian dynasty of the franks
conquered and established a kingdom in italy
crossed the english channel and conquered britain
drove the vikings out of scandinavia
ruled over a kingdom including most of modern-day france, the low countries, and western germany

Ruled over a kingdom including most of modern-day France, the Low Countries, and western Germany.

Explanation:

The Merovingian was the largest and most powerful kingdom of western Europe after the collapse of the Western Roman Empire.

The Merovingian dynasty was the royal family of the Franks since the 5th century and up to 751. They managed to unite under their rule all the Franks, the northern Gaulish Romans, he Visigoths, the Burgundians, Raetia, the Alemanni, Bavarii and Saxons.