Around 2500 bc (Approximately when the Great Pyramid of Giza was build) we're talking about the latter half of the early bronze age (EBA III). Cultures around this time in central Europe are predominantly semi-nomadic tribes (seasonal camps) where the first writings and settlements in these areas are starting to develop.

The Mierzanowice culture was predominant during that time in eastern Poland, Western Poland was as of current knowledge unsettled. As far as it goes the culture was nothing extremely noteworthy for its time. Normal tools, weapons and cultural signs for its time. Archeological sites consist mainly of cemeteries, and as far as I know no major ruins or settlement have ever been found.