The coastlines of our world seem almost immutable, but this is merely an illusion born from the brevity of human life. With the ebb and flow of the great ice sheets, sea levels have risen and fallen many times since humans first walked the Earth, causing the shores to shift and migrate.

Between ten and fifteen thousand years ago, during the gradual retreat of the ice sheets that marked the end of the last glacial period and before widespread farming, swamps to the north blocked the waters which now form the North Sea. The Narrow Sea between present-day Britain and France was a turbulent torrent fed by immense rapids and swept by powerful tidal currents, draining much of Northern Europe. Sea levels were lower than in today's Straits of Dover, and the chalk cliffs of the South Foreland and Cap Blanc — sculpted by waves during even earlier periods of high sea level — stood as great inland cliffs, bordered by forested coastal plains.

The now-submerged plain on the southern side of the Narrow Sea was home to warring tribes who had over-hunted the local game to such an extent that, at the time of these events, they teetered on the brink of starvation. As the world around them slowly transformed with the retreating ice, people faced an uncertain future, unaware that the end of the last ice age would herald the dawn of a new era for humanity.