Why did Roman rule in the Low Countries end during the early 5th century?

Roman rule in the Low Countries effectively ended in the early 5th century due to a massive invasion by Germanic tribes in 406–407 CE.1

While the Roman Empire had previously attempted to manage the region by tolerating Germanic penetration and employing certain tribes—such as the Franks settled in Toxandria—to defend imperial borders, this strategy ultimately failed to prevent the collapse of Roman occupation. By the mid-5th century, the Franks had assumed control of the border areas, marking the transition away from Roman administration. This shift was part of a broader period of instability across the Western Roman Empire, characterized by neglected frontiers and the movement of various Germanic groups into Roman territories.123