The 16th-century Pomeranian chronicler Thomas Kantzow also states that Swietopelk was one of the younger sons of Swietibor, who ruled Eastern Pomerania after his father was deposed.
[5] Other historians have also hypothesized that Swietopelk and Swietibor were related, by blood or by marriage, to the Polish Piast dynasty, or that they served as voyevodas for them in Gdańsk (Danzig).
[7] After Swietopelk tried to carry out foreign policy without approval of the Polish ruler in 1112, Krzywousty invaded his lands.
Swietopelk had to pay a tribute to the Polish duke and gave his son (name unknown) as a hostage.
However, others consider the "Odrzanski" Swietopolk to have been a different person, Duke of the Chyżans (Kcynians), whose lands were invaded in 1121 by the Saxon prince Lothar of Supplinburg.