The Bronze and Iron Age cultures in Poland are known mainly from archeological research. Early Bronze Age cultures in Poland began around 2300–2400 BCE, while the Iron Age commenced in approximately 700–750 BCE. The Iron Age archeological cultures no longer existed by the start of the Common Era. The subject of the ethnicity and linguistic affiliation of the groups living in Central Europe at that time is, given the absence of written records, speculative, and accordingly there is considerable disagreement. In Poland the Lusatian culture, spanning both the Bronze and Iron Ages, became particularly prominent. The most famous archeological finding from that period is the Biskupin fortified settlement (gord) on the lake from which it takes its name, representing the Lusatian culture of the ea