The settlement of Prussia by the Teutonic Order was by no means the only venture of German colonization in the east. Charlemagne’s, successful subjugation of the Saxons may be considered one of the earliest moves of eastern expansion. This took the Germans to the river Elbe, an ideal position from which to penetrate further eastward. There were several marches of the Reich, established for protection against the heathens such as the Wends and the Slavs. The marcher territory of Brandenburg, the Mark Brandenburg, was one of these, its origin lying in the period of Charlemagne’s reign. It was subdivided into various parts, the most important of which, almost coinciding in terms of territory with the later Mark Brandenburg, was the Nordmark. This consisted of all the German-colonized territories on the west bank of the river Elbe, later to be called the Altmark. From the Altmark trade developed with the Wendish neighbours; it formed the base of power and supplies for war with them, as well as missionary activity. Already in the tenth century, under Otto the Great, two dioceses were established in Havelberg and Brandenburg, supervised by the bishopric of Magdeburg which had been founded in 968. An uprising of the Wends against their new masters and new religion had put a temporary end to these dioceses, and it was only in the twelfth century, as part of the general crusading fervour and the beginnings of a further German movement eastwards in which the Teutonic Knights were later to take part, that German settlement east of the Elbe was firmly re-established. This process of colonization of the east had basically little to do with imperial policy, whose focus of political and military attention lay to the south of Germany, in Italy. Rather it was the policy of several of the German territorial princes, notably Henry the Lion, who, as vassal of Frederick Barbarossa, fell out with him when he refused to support the crusade to the Holy Land, seeing his primary mission within Germany and its eastern expansion.