The history of the southwest of France, like that of France in general, is marked by a series of invasions and conquests. Apart from prehistoric peoples—largely in the Perigord—the earliest inhabitants of the southwest were Gauls, a Celtic people. The Gauls maintained control of the southwest until conquered by the Romans in 52 B.C. Rome controlled the Aquitaine until its capital and power shifted east to Constantinople, at which time the borders of Gaul were overrun by Germanic invaders who divided the land into small chiefdoms. While the territory of Gaul was reunified under the Frankish king Clovis, who ascended the throne in A.D. 481, a succession of French kings—including the emperor Charlemagne, who was a force in the revival of Latin culture—struggled with variable success until the period of Absolutism in the seventeenth century to bring France under unified rule. The southwest was characterized by fiercely independent landlords or seigneurs who used their feudal domains and local power over the peasantry with some success to hold at bay the French crown. They were gradually less able to resist assimilation as a national market took shape during the sixteenth and seventeenth centuries. The twelfth to fifteenth centuries witnessed the occupation of the southwest by the English. This period was important for the growth of the southwest French wine trade as winegrowers found an eager clientele for claret among the English aristocracy. The importance of the wine trade can be recognized in the fact that English warships of this period were measured by the quantity of wine they could carry. The Aquitaine also served as a stronghold for the Protestant Huguenots during the sixteenth and seventeenth centuries, who suffered persecution at the hands of the Catholic church. The Huguenots called upon the English crown for assistance against the Catholic Cardinal Richelieu. The profound cultural and economic ties of the southwest of France to England, beginning with the occupation and reinforced during the religious wars, persist today, as evidenced by the numerous English people who have settled in this region. From the period of French Absolutism onward through the French Revolution, which was well supported in the southwest, the Napoleonic empires, and now the Fifth Republic, the Aquitaine's history—but not its complete cultural identity—converges with that of the French nation-state. The southwest is ethnically diverse, especially in urban areas. Periods of recent economic hardship, however, have led to racial and ethnic tensions in the Aquitaine.