The history of the Netherlands is the history of seafaring people thriving on a lowland river delta on the North Sea in northwestern Europe. Records begin with the four centuries during which the region formed a militarized border zone of the Roman empire. This came under increasing pressure from Germanic peoples moving westwards. As Roman power collapsed and the Middle Ages began, three dominant Germanic peoples coalesced in the area, Frisians in the north and coastal areas, Low Saxons in the northeast, and the Franks in the south.