An isthmus of swampland named The Neck separates the North from the South. It is home to short, marsh-dwelling crannogmen ruled by House Reed of Greywater Watch, loyal bannermen of House Stark. The Neck's difficult wetland terrain is infested by predatory lizard-lions, restricting the only dryland passage to the causeway commanded by the almost impenetrable stronghold of Moat Cailin, which protected the North from land invasion from the south. The city of White Harbor, located at the mouth of the White Knife river, is a thriving port and the fifth largest settlement in the Seven Kingdoms.