During the Neolithic the local population had grown from hundreds to perhaps a few thousand people. This process gathered pace in the Bronze Age, which is named after the arrival of metal-workers in Britain, around 2500 BC. As the population grew it became necessary to divide-up the landscape into field systems; some of the earliest fields in England are found in Peterborough.
Meanwhile North Sea levels were steadily rising and the nearby floodplain of the River Nene became permanent Fen. Animals were grazed on its lush summer pastures. Major sites of this time have been found at Fengate, Must Farm and Bradley Fen.