Mieszko the Younger time in 1166 or 1167 in a document signed between Mieszko III and Casimir II the Just at the congress in Jędrzejów as one of the sons of the Duke of Greater Poland. Between 1177 and 1179, as a result of the revolt against his father, Mieszko, with his parents and siblings, were exiled from Poland. They probably returned to the country in 1181, when Mieszko III regained the rule over Greater Poland. In 1184 and thanks to the wise diplomatic affairs of his father, Mieszko the Younger was appointed by the sickly Duke Leszek Governor of the Masovian-Kuyavian principality,
Mieszko II the Fat which was given to their mother Viola as her . Mieszko II the Fat Mieszko II the Fat () ( – 22 October 1246) was a Duke of Opole-Racibórz from 1230 until his death, and Duke of Kalisz-Wieluń during 1234–1239 (with his brother as co-ruler). He was the eldest son of Duke Casimir I of Opole by his wife Viola, probably a Bulgarian lady. At the time of his father's death in 1230, Mieszko II and his younger brother Władysław were still minors; for this, the regency of the Duchy was taken by their mother and Henry I the Bearded,