Polish tribes
"Polish tribes" is a term used sometimes to describe the tribes of West Slavic Lechites that lived from around the mid-6th century in the territories that became Polish with the creation of the Polish state by the Piast dynasty. The territory on which they lived became a part of the first Polish state created by duke Mieszko I and expanded at the end of the 10th century, enlarged further by conquests of king Bolesław I at the beginning of the 11th century.
In about 850 AD a list of peoples was written down by the Bavarian Geographer. Absent on the list are Lechitic-speaking Polans, Pomeranians and Masovians, who became known later and were written about by Nestor the Chronicler in his Primary Chronicle (11th/12th century).
The most important tribes who were conquered by Polans were the Masovians, Vistulans, Silesians and Pomeranians. These five tribes "shared fundamentally common culture and language and were considerably more closely related to one another than were the Germanic tribes."