Context: The Period of Division from, A.D., 1138 – A.D., 1314, which included nearly 200 years of feudal fragmentation and which stemmed from Bolesław III's division of Poland among his sons, was the genesis of the social structure which saw the economic elevation of the great landowning feudal nobles (możni/Magnates, both ecclesiastical and lay) from the rycerstwo they originated from. The prior social structure was one of Polish tribes united into the historic Polish nation under a state ruled by the Piast dynasty, this dynasty appearing circa 850 A.D.

Question: WHen was the period of Division?
Answer: A.D., 1138 – A.D., 1314

Question: What stemmed the period of division?
Answer: Bolesław III's division of Poland among his sons

Question: What tribe was the prior social structure from?
Answer: Polish

Question: WHen did the Piast dynasty appear?
Answer: 850 A.D.

Question: Polish nation ruled by what dynasty?
Answer: Piast dynasty,