The Franks presumably arose from various western Germanic tribes originally living between the Rhine and Weser rivers.
In the beginning, they were not a unified tribe yet but consisted of several bands under their own leaders.
Since the middle of the 3rd century some of them attacked the Imperium Romanum, the large Roman Empire.
In Late Antiquity, the Roman Empire was already weakened by domestic strife and since 395 it was divided into the Eastern Roman Empire and the Western Roman Empire.
While East Rome continued to exist as the Byzantine Empire, the West Germanic tribes contributed to the final fall of the Western Roman Empire in 476 by their conquests during the time of the so-called Great Migration.
Also in the Roman province referred to as Gaul by the Romans, large Germanic tribes established themselves, among them Western Goths, Burgundians and Alemanni as well as Franks, and created their own small realms.