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,
Spytihněv I, Duke of Bohemia Spytihněv I, Duke of Bohemia Spytihněv I (c. 875 – 915), a member of the Přemyslid dynasty, was Duke of Bohemia from 894 or 895 until his death. He was the eldest son of Duke Bořivoj I, the first historically documented Bohemian ruler, and his wife Ludmila. Spytihněv and his younger brother Vratislaus were still minors at the time of their father's death about 889, and the Bohemian lands were placed under the regency of their suzerain, the Great Moravian ruler Svatopluk I. After Svatopluk died in 894, an inheritance conflict arose between his sons Mojmír II and Svatopluk II.