The earliest references to Polish territories appear in the works of 1st- and 2nd-c. AD Roman and Byzantine authors (Tacitus, Ptolemy, Pomponius Mela, Jordanes, Procopius of Caesarea). In the 6th c. AD Slavonic tribes arrived on the territories of present-day Poland and subsequently became the dominant group in the area. Not only were they able to establish strong administrative centres like Wiślica, Poznań, and Gniezno with power structures based on tribal assemblies under a chieftain, trading settlements like Szczecin or Wolin, and focal points for religious worship like Mt. Ślęża, but they withstood invasions by nomadic tribes from Asia and attacks by the neighbouring principality of Great Moravia.
Around 850 AD in Descriptio civitatum et regionum ad septentrionalem plagem Danubii (A Description of the Cities and Regions North of the Danube) Geographus Bavarus enumerated several Slavonic tribes - Goplanians, Dziadoszanians, Silesians, Bobrzanians, Opolanians, Vislanians and Lędzianians - inhabiting the Vistula and Oder basins. A rising volume of trade contributed to the growth of settlements the along the trade routes which would be fortified on account of the wars; while the role of the chieftain, and later tribal prince, increased. This process was most manifest in Greater Poland(Wielkopolska), where the Polanian tribe quickly reached ascendancy and by the mid-tenth century was expanding to lands adjoining them on the east (Mazovia) and west (the Lubusz Region and Lusatia). The Polanians gradually subjugated the neighbouring Slavonic tribes, creating a uniform principality with an efficient administrative system.