families. The clan system survived in this way throughout the whole of Polish history. It is evident that the warrior class in Poland had quite a different origin and a different legal and social position from that of the feudal nobility of Western Europe.
Owing to the adoption of the Roman faith and the struggle against the German Empire, which led the rulers of Poland to interfere in the affairs of Bohemia and Hungary, Poland entered into close communion with the West, particularly with the German Empire, and this resulted in the gradual penetration into the country of Western ideas and Western institutions. Thus among others the mediaeval custom of dividing the country among the sons of the ruler on his death was adopted in the twelfth century. It was most disastrous for a kingdom like Poland, which was surrounded by powerful enemies and which had not yet quite reached its natural frontiers and had not sufficiently strengthened its position on the Baltic.
The Slavonic populations on the Baltic coast, west of the Vistula, had only recently been incorporated into the Polish State, while to the east of the Vistula a Lithuanian tribe of Prussians had remained independent and pagans, the missionary work carried on among them from Poland having proved unsuccessful. Divided Poland was unable to complete the task of conquering the Baltic coast, and in this way the field was open for the Teutonic Order. The Knights of the Cross established there a German stronghold which later on became one of the foundations of German Prussia and the greatest danger to the independence of Poland.
