As the historian looks back into this age, he is, therefore, able to find broad traces of much that is regarded as fundamental to modern life. Of first importance in this regard is the employment of popular idioms in literary productions. French literature saw its beginnings in the eleventh century with the _chansons de geste_, songs of valorous deeds from the heroic age of the Frankish kingdom. In the next century the poets began to use the themes of the Arthurian legends and sang the exploits of the famous British king and the knights of his Round Table. A little later came another cycle of poems based on the heroic tales of classical antiquity. The twelfth century witnessed a parallel movement in Germany, which at first was largely an imitation of contemporary French poetry. The poets, however, soon discovered literary treasures in the dim world of the Teutonic past, in the tales of the Nibelungs, in the heroic deeds of Theodoric, and in the exploits of other heroes. Thus in the first half of the thirteenth century there was a large body of French and German verse in circulation. The verses were borne from region to region and from land to land by professional entertainers, who chanted the poems, and by pilgrims and other travelers, who secured manuscript copies. In the course of time the new tales reached the Northern countries, and it was not long before the Northmen were eagerly listening to the stories of chivalrous warfare, militant religion, and tragic love, that they had learned in the southlands. The Northern peoples thus had a share in the fruitage of the later middle ages; but they also had a share in their achievements. Politically as well as intellectually the thirteenth century was a great age in the Scandinavian countries. The Danish kingdom rose to the highest point of its power under Valdemar the Victorious, whose troubled reign began in 1202. Valdemar succeeded in extending the territories of Denmark along the entire southern coast of the Baltic Sea; but the greatness was short-lived: after the defeat of the Danes by the North Germans at Börnhoved in 1227, the decline of Danish imperialism began. In Sweden, too, men dreamed of conquest beyond the sea. Under the leadership of Earl Birger, the most eminent statesman of medieval Sweden, Swedish power was steadily extended into Finnish territory, and the foundations of Sweden as a great European power was being laid.