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 probably closer to the latter date. Due to the lack of sources it is not possible to determine exactly which lands he inherited. Certainly among them were the areas inhabited by the Polans and Goplans, as well as the Sieradz-Łęczyca lands and Kuyavia. It is possible that this state included also Masovia and Gdańsk Pomerania. Soon the new ruler had faced the task of integrating the relatively large, ethnically and culturally heterogeneous territory. Although the residents of areas controlled by Mieszko spoke mostly one language, had similar beliefs and reached a similar level of economic and general development, they were