The oldest known mention of Żerków comes from a document of Duke Bolesław the Pious from 1257, and in a document of Duke and future King of Poland Przemysł II from 1283 it was already referred to as a town. Żerków was a private town of Polish nobility, administratively located in the Pyzdry County in the Kalisz Voivodeship in the Greater Poland Province of the Polish Crown.
The earliest recorded reference to Żerków dates back to a document by Duke Bolesław the Pious in 1257, and by 1283 it was already mentioned as a town in a document by Duke Przemysł II, who would later become King of Poland. Żerków was a private town owned by Polish nobility, situated administratively in Pyzdry County within the Kalisz Voivodeship in the Greater Poland Province.