The Franks ( or ) are historically first known as a group of Germanic tribes that roamed the land between the Lower and Middle Rhine in the 3rd century AD, and second as the people of Gaul who merged with the Gallo-Roman populations during succeeding centuries, passing on their name to modern-day France and becoming part of the heritage of the modern day French people. Some Franks raided Roman territory, while other Frankish tribes joined the Roman troops of Gaul. In later times, Franks became the military rulers of the northern part of Roman Gaul. With the coronation of their ruler Charlemagne as by Pope Leo III in 800 AD, he and his successors were portrayed as legitimate successors to the emperors of the Western Roman Empire.