History of Poland during the Piast dynasty of Lesser Poland, the country of the Vistulans, and of Silesia (both taken by Mieszko from the Czech state during the later part of the 10th century), Mieszko's state reached its mature form, including the main regions regarded as ethnically Polish. The Piast lands totaled about in area, with an approximate population of under one million. Initially a pagan, Mieszko I was the first ruler of the Polans tribal union known from contemporary written sources. A detailed account of aspects of Mieszko's early reign was given by Ibrâhîm ibn Ya`qûb, a Jewish traveler, according to whom Mieszko was one of
Mieszko I of Poland Mieszko allied his country with Sweden against Denmark. The alliance was sealed with the marriage of Mieszko's daughter Świętosława with the Swedish king Erik. The content of the treaty is known from the not entirely reliable, but originating directly from the Danish court tradition account given by Adam of Bremen. In this text, probably as a result of confusion, he gives instead of Mieszko's name the name of his son Bolesław: Mieszko decided on the alliance with Sweden probably in order to help protect his possessions in Pomerania from the Danish King Harald Bluetooth and his son Sweyn. They may