As the shallow sea slowly silted up, the boggy ground was taken over by massive reed beds ideal breeding grounds for vast shoals of fish and flocks of water fowl. Larger animals like deer abounded and attracted other less welcome interest from the wolves that were common place in England at the time. This abundant bounty was also the centre of attraction for early humans, the Hunter-Gatherers. For them the larder provided by the Anglian Fen was too good to miss.
But food was not the only reason that the Fen was a good place to live, it also provided fresh water, wood with which make weapons and build houses, and reeds to roof them with. The shelter and protection afforded by the Fen was also very important, a stranger was easily lost or drowned in the marshes. You don’t need a castle if your enemy cannot find you!
See Ouse Fen Nature Reserve..