Mieszko I of Poland mentions a gift or dedication of Mieszko's land to the Pope (the act took place almost a hundred years earlier). It is roughly his borders that Poland was returned to in 1945. There is no certain information on Mieszko I's life before he took control over his lands. Only the "Lesser Poland Chronicle" gives the date of his birth as somewhere between the years 920–931 (depending on the version of the manuscript), however, modern researchers don't recognize the Chronicle as a reliable source. Several historians on the basis of their investigations postulated the date of Mieszko I's birth to have
Bolesław I the Brave Mieszko II) that gave the King his widely known nickname of "Brave" (Polish: "Chrobry") -later Gallus Anonymus in the Chapter 6 of his "Gesta principum Polonorum" named the Polish ruler as "Bolezlavus qui dicebatur Gloriosus seu Chrabri". The contemporaneous Thietmar of Merseburg recorded Bolesław's marriages, also mentioning his children. Bolesław's first wife was an unnamed daughter of Rikdag, Margrave of Meissen. Historian Manteuffel says that the marriage was arranged in the early 980s by Mieszko I who wanted to strengthen his links with the Saxon lords and to enable his son to succeed Rikdag in Meissen. Bolesław "later sent her