Boles³aw Krzywousty (Boleslaus the Wry-mouthed). Fragmentation

   The reign of Boleslaus the Wry-mouthed (nephew of Boleslaus the Bold) could not stop the country's decline. The  Wry-mouthed  gained renown for his military achievements (victory against the Empire in 1109, and the defeat of Pomerania in 1113-19), but on his deathbed in 1138 he divided up his realm, distributing a province to each of his sons. The period of feudal dismemberment lasted over a century and a half, during which Poland's status diminished, and would not be retrieved until the mid-14th century.
    However, this was a period of social stability and rapid advancement, despite several devastating Mongol invasions. Issues of land tenure were regulated: knights were enfeoffed (granted property in exchange for feudal service to the prince); thousands of new villages and many towns were founded. Numerous settlers came from Germany, and some from the Low Countries settled on the Baltic coast. Scores of monasteries and priories sprang up, mostly Cistercian and Dominican foundations.