Geography of Poland today's modern Polish society. The ancestors of today's Poles, the Polanie, built their first fortresses on islands in these lakes. The legendary Prince Popiel ruled from Kruszwica tower erected on the Lake Gopło. The first historically documented ruler of Poland, Duke Mieszko I, had his palace on an island in the Warta River in Poznań. Nowadays the Polish lakes provide a location for the pursuit of water sports such as yachting and wind-surfing. The Polish Baltic coast is approximately long and extends from Świnoujście on the islands of Usedom and Wolin in the west to Krynica Morska on the Vistula
Mieszko I of Poland in the hands of Bohemia. Sandomierz under this scenario was the central hub of the area, with Czerwień, Przemyśl and Chełm assuming the function of defensive borderland strongholds. After the death of Emperor Otto I in 973 Mieszko, like his brother-in-law, Duke Boleslav II of Bohemia, joined the German opposition in support of the attempted imperial succession of Henry II, Duke of Bavaria. Mieszko may have been motivated by revenge because of the (presumably) negative verdict of the Quedlinburg summit, but, more importantly, he may have wanted more favorable terms for his cooperation with Germany. The participation of Mieszko in