German-speaking peoples first entered the historical record when tribal groups migrating southward reached the Roman frontiers along the Rhine and the Danube. Some crossed over and merged with southern or western European populations; others stayed behind to farm or to build on the outposts abandoned by Rome. In the Middle Ages, the area now known as Germany presented a variegated sociogeographic landscape, characterized by both peasant agriculture and riverine and coastal commerce. Rival royal and noble houses sought to establish administrative bases through expanding their domains, controlling clerical appointments, or, by the thirteenth century, colonizing the eastern marches. As the struggles among emperors, popes, and nobles continued, many cities enjoyed political autonomy and prosperity. Urban manufacture and commerce suffered during the Religious wars, when the German princes tried to co-opt the church administration and consolidate their territories. Conflicts beginning with the Protestant Reformation culminated in the Thirty Years' War, which devastated central Europe economically and fragmented it politically. By 1648 Germany was divided into more than 300 small principalities. France's revolutionary army struck the first blow for centralization by bringing western Germany under direct French rule and organizing the rest of Germany into a handful of tributary states. On the eve of Napoleon's defeat, Germany spawned a nationalist movement that in many ways anticipated similar movements in eastern Europe and the third world. Because of its famous army and the industrial strength of its newly acquired Rhine Province, Prussia prevailed over Austria in the struggle for intra-German hegemony. Germany was united in 1871 under a partially liberalized but still largely autocratic Prussian regime. Germany's bid for global hegemony failed in World War I and again under Hitler in World War II. In 1949 the zones occupied by the French, British, and Americans combined to form the Federal Republic of Germany (West Germany), and later that same year the Soviet zone became the German Democratic Republic (East Germany). The two German states persisted as Western and Soviet client states until 1989, when reform in the Soviet Union contributed to the fall of the East German regime. The new German currency union was formed on 1 July 1990, and political unification followed on 3 October.