History of Poland in the Middle Ages

In this time period Polish history covering roughly a millennium, from the 5th century, the way through to the 16th century. It is commonly dated from the fall of the Western Roman Empire, and contrasted with a later Early Modern Period; the time during which the rise of humanism in the Italian Renaissance and the Reformation unfolded, are generally associated with the transition out of the Middle Ages, with European overseas expansion as a succeeding process, but such dates are approximate and based upon nuanced arguments.

The first waves of Slavic migration settled the area of the upper Vistula River and elsewhere in the lands of present-day southeastern Poland and southern Masovia, coming from the upper and middle regions of the Dnieper River. Results of a genetic study by researchers from Gdańsk Medical University "support hypothesis placing the earliest known homeland of Slavs in the middle Dnieper basin". The West Slavs came primarily from the more western early Slavic branch called the Sclaveni by the Byzantine historian Jordanes in Getica, the eastern branch being the Antes. The Slavs had first migrated into Poland in the second half of the 5th century, some half century after these territories had been vacated by Germanic tribes (after a period during which settlements were absent or rare). According to the references given in this and Poland in the Early Middle Ages article, many scholars now believe that the Slavic tribes had not been present in Poland before the earliest medieval period, though the opposite view, predominant in Polish prehistory and protohistory in the past, is still represented.

...
Wikipedia