Around the middle of the third century CE, a certain group among the many Barbarian tribes began to coalesce into a larger super-tribe along he east bank of the Upper Rhine River. They called themselves the Franks, meaning fierce or free. They did not raid Gaul substantially, since they were not able to develop any political unity and were led by several kinglets. With the beginning of the large-scale barbarian invasions of the fourth century, the Romans found them useful auxiliaries and foederati, allowing them to settle on the west side of the Rhine. These Franks that crossed over were called the Salic Franks, and located mostly to northeastern Belgium. Unlike other Barbarians, they began to cultivate the area heavily, as they were possessed of a substantial peasant element. They did not go through a process of Romanization akin to the Goths', and did not adopt Christianity. In 406, when Rhadagaesius led the great Barbarian contingent over the Rhine, the Franks, who were not able to hold them back, stayed where they were, lacking political unity or a taste for Roman civilization.
In the next fifty years, Gaul withered economically from its earlier status as a copy of Roman civilization to the south. After the Huns in the 450s, all the Barbarians settled through hospitalitas left the areas allotted to them and created kingdoms. Aegidius, the last Roman (though German) general in Northern Gaul, made himself the political leader of the area's Romans. Cut off from Italy by Burgundians, Visigoths, and others, he relied for warriors on indigenous Barbarians: the Franks. On two occasions he hired a Frankish chieftain named Childeric to help, once perhaps in a battle with the Visigoths at Orleans (463). During this period from the 450s to the 480s, the nature of Frankish activity in Gaul changed: a) different chiefs raided deeper into the political vacuum of Gaul, at the same time as they jockeyed with each other for popularity and preeminence based on an ability to attract armies looking for booty; and b) Frankish peasants crossed the Rhine in greater numbers, not returning after raiding, but settling, founding villages. The raids were lucrative, and certain petty kings were able to get the trappings of royalty. Childeric was able to build a palace in Tournai, decorated with stolen treasures. At his death in 481, Frankish domains straddled the Rhine, pushing into Gaul.
Childeric's son was Chlodovecus, or Clovis. Though his father's expansion had been unspectacular, he did inherit some wealth, a supposed lineage going back to Germanic gods, as well as Frankish warriors' expectations that he would continue his father's raiding success. The first opportunity came in 486. Aegidus' son Syagrius was in control of North-central France stretching to the Visigothic domains, and at the Battle of Soissons, Clovis defeated him, opening the area to settlement of thousands of Frankish peasants. This was the demographic basis of Frankish rule. He then spent the next decade in obscure campaigns eliminating rival Frankish leaders. Then in 596, he defeated the Alamanni in Eastern-Central Gaul, expanding his kingdom further.
Sometime between 496 and 507, Clovis converted to Catholic Christianity, after a brief Arian transition phase. His baptism by the bishop of Rheims was followed immediately by the conversion of 3000 of his troops, after which the rest of his people converted. This meant that while other Germans, including Theodoric's Goths in control of Italy, were Arian and viewed heretically by the Church, Clovis could present himself and his kingdom as the only legitimate Catholic ruler in the region. Gallo-Roman bishops cooperated with the Franks, and some, like Gregory of Tours, went on to present his conquests, starting with that of the Alamanni, as stemming from Catholic convictions. At this point, Clovis began pressuring the Visigoths in southwestern Gaul, whose leader Alaric II had been exiling Catholic bishops no longer willing to cooperate with the Arian ruler. Finally, in 507 he moved in force against the Visigoths. Gregory casts him as saying he could no longer tolerate Arian rule in southern Gaul. Crossing the Loire, he routed Alaric II's forces at the Battle of Vouille, sacked Visigothic cities, and forced them to flee to Spain. It is at this time that Theodoric the Ostrogoth expanded into Provence. In 508, Clovis went to Tours and assumed the Imperial Tunic in the form of an honorary consulship bestowed by Eastern Emperor Anastasia who was showing his disquietude with Theodoric's rule. Clovis then issued the Salic Laws, the first written code of Frankish law. Catholic bishops helped in its preparation, and it gave him the appearance of a proper ruler. By his death in 511, he had created a totally new political unit, Regium Francium. It included all of Roman Gaul and the old Germanic reservations with the exception of the Burgundian kingdom. Further, he had eliminated all other Frankish kingly families, leaving only his own. His conversion to Catholicism removed a bar to Frankish-Gallo-Roman intermarriage.
It is with the Frankish assumption of dominion in Gaul that the Dark Ages reached this region. Not all have felt this way. In the beginnings of the twentieth century, a Belgian socio-economic historian named Henri Pirenne tried to revise the view that the Barbarian migrations spelled the doom of the Antique in Europe. According to him, as the Barbarians came to enjoy Roman society rather than destroy it, one had to look elsewhere, and later, for the decomposition of Mediterranean civilization based on long-distance commerce and high culture. For him, it was the Islamic expansion, which brought a war-like band of Arabs into domination of the trade routes. Not at all inclined towards trade, they strangled the Mediterranean basin, ushering in the impoverished early Middle Ages.
There are several problems with this perspective. First, everything we know about Islamic commercial relations from the 600s on suggests that they were quite positively predisposed towards cultivating both internal trade and long- distance, international commerce. Not only did trade provide them with commodities and funds they needed in an expanding civilization, it also provided Islamic rulers with finances in the form of customs revenue. Second, Pirenne, writing at a time of Western economic dominance over the Middle East, perhaps forgot that Muhammad himself had been a long-distance merchant in Arabia and Syria, and that the elites of early Islam all came from a similar background. We even are indebted to Muslims for such innovations as the check, as well as risk and profit-sharing mechanisms permitting the funding of inter-regional trade, called mudaraba in Arabic and commenda in Latin. These were used widely in the emerging Italian merchant cities from the tenth century onwards. Third, more recent historians have shown that where Eastern-origin commodities did start to disappear from European markets after the rise of Islam, it was often due to hording by European rulers, or monopolizing by governments. In other respects, such commodities had become scarce prior to Islam's emergence.