Complex sentence: The pole lathe's origin is lost in antiquity; we know that Vikings used them from the archaeological finds at Jórvík, the Viking settlement discovered beneath the modern city of York in England.
Split into simpler sentences: The pole lathe's origin is lost in antiquity; we know that Vikings used them from the archaeological finds at Jórvík. Jórvík is the Viking settlement discovered beneath the modern city of York in England.