The barbarian kingdoms, also known as the post-Roman kingdoms, the western kingdoms or the early medieval kingdoms, were the states founded by various non-Roman, primarily Germanic, peoples in Western Europe and North Africa following the collapse of the Western Roman Empire in the fifth century. The formation of the barbarian kingdoms was a complicated, gradual and largely unintentional process, as the Roman state failed to handle barbarian migrants on the imperial borders, leading to both invasions and invitations into imperial territory, but simultaneously denied barbarians the ability to properly integrate into the imperial framework. The influence of barbarian rulers, at first local warlords and client kings without firm connections to any territories, increased as Roman emperors and usurpers used them as pawns in civil wars. It was only after the collapse of effective Western Roman central authority that the barbarian realms transitioned into proper territorial kingdoms.
The barbarian kings of the west drew on legitimacy through connecting themselves to the Roman Empire in order to strengthen their rule. Virtually all of them assumed the style dominus noster ("our lord"), previously used by the emperors, and many assumed the praenomen Flavius, borne by virtually all Roman emperors in late antiquity. The kings typically also assumed a subordinate position in diplomacy with the remaining Eastern Roman Empire. The barbarian kings also adopted many aspects of the late Roman administration, but the old Roman system gradually dissolved and disappeared over the centuries, accelerated by periods of political turmoil. The major difference between the administration of the old Western Roman Empire and the new royal administrations was their scale, as the barbarian governments, on accounts of controlling significantly less territory, were less deep and less complex. As a result, there was a considerable breakdown in living standards as well as social and economic complexity. For the most part, the barbarian kingdoms were highly fragile and ephemeral. By the time of the coronation of Charlemagne, king of the Franks, as emperor in 800, the event usually seen as marking the end of the age of the barbarian kingdoms, only the Frankish kingdom remained out of the once vast and diverse network of kingdoms.