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 I of Poland which facilitated the development of trade. Amber, fur and salt (extracted in Kuyavia and around Kołobrzeg) were exported to other countries, while cloth, crafts, tools and ornaments were imported. According to Gallus Anonymus, before becoming a Roman Catholic Mieszko had seven pagan wives, whom he was required to relinquish, leaving Dobrawa as his only spouse. Nothing is known of the fates of any possible children from these relationships. In 965, before his baptism, Mieszko married Dobrawa (b. 940/45 – d. 977), daughter of Boleslav I the Cruel, Duke of Bohemia. They had two children: According to one hypothesis there was