The Northwest Europe category is a very random grouping of mountains. It is a large area that includes everything north of the Alps and the Pyrenees: Great Britain, Ireland, the Low Countries, Denmark, and most of France and Germany. When it comes to mountain ranges, the main unifying terrain characteristic of this area is low, rolling hills with very few areas of real mountains. Elevations never rise above 2000 meters, and in most of the area hills above 1000 meters are rare.
The eastern border of this area is arbitrary, since the lowlands of Eastern Europe are very similar to the lowlands of Northwest Europe. Also, it is unusual to include large islands like Great Britian and Ireland with areas on the continent, but the terrain on both sides of the narrow English Channel shows topographic similarity.
Historically, culturally, politically, and economically, this small area has played a strikingly disproportionate role in world affairs. The low rolling hills and fertile countryside here sustained the cities of Paris, London, Amsterdam, and Berlin, all seats of empires that together emcompassed half the world. So these low peaks have seen an unusual amount of scrutiny over the years.