Norfolk's coastline is markedly different from the coastline that existed when the Romans first occupied what is now the county of Norfolk. The northern coast of Norfolk has eroded over the last two millennia, parts of it perhaps having retreated by up to . The eastern coast was dominated by an enormous estuary, the island of Flegg and a peninsula (modern Lothingland). The Wash was much larger in size and the area now known as the Fens was impenetrable marsh containing isolated islands surrounded by water. The River Waveney between Norfolk and Suffolk was at that time a substantial feature.