Leszek I the White
Swietopelk was the son of the Pomeranian duke Mestwin I and his wife Swinisława. His father had ruled over Eastern Pomerania (or Pomerelia) since about 1205 by appointment of the Polish high duke Władysław III Spindleshanks. In 1216 or 1217 his son Swietopelk was made a steward over Pomerelia by High Duke Leszek I the White of Kraków. He was responsible for the Gdańsk territory, the largest of the four portions of Pomerelia. In 1218, Swietopelk took advantage of a revolt of local knights against Danish rule to occupy the Lands of Schlawe and Stolp. After his brother Warcislaw died without heirs, Swietopelk took over his Lubiszewo Tczewskie.