It was split into Upper and Lower divisions following a succession crisis resulting from the death of Boleslaw III, fracturing the work of Mieszko I who had helped gain control of it.  
It was split into Upper and Lower divisions following a succession crisis resulting from the death of Boleslaw III, fracturing the work of Mieszko I who had helped gain control of it.  Geographically, the Beskid mountains delineate its southern borders while the Orlicke and Opawskie mountains are part of a range forming its southwest boundary. Cities like Opole and Bytom lie along the river which dominates most of its landscape.  This region's fate following World War I was determined by a plebiscite, although its upper half, spurred by Wojciech Korfanty, underwent three namesake uprisings and seceded two years later.  Earlier, the region was divided into Opava, Cieszyn and Krnov districts which were for about a century adjoined to Moravia after the 1748 Treaty of Aix-la-Chapelle which ended a war over it.  With Wrocklaw, Katowice and Ostrava as major cities, and presently shared between Germany, the Czech republic and (mainly) Poland, FTP, identify this area conquered by Frederick the Great in the War of Austrian Succession.
It was split into Upper and Lower divisions following a succession crisis resulting from the death of Boleslaw III, fracturing the work of Mieszko I who had helped gain control of it.  
{Silesia} (also accept {Slask}, {Slezsko} or {Schlesien})