You will have to do a little bit of research, here is a hint:
in the entry entitled North European Plain
"major reference (in European Plain (plain, Europe): Physiography)
...all of western and northern France, Belgium, The Netherlands, southern Scandinavia, northern Germany, and nearly all of Poland; from northern France and Belgium eastward it commonly is called the North European Plain. In the east the plain generally is called the East European, or Russian, Plain."
Nope. Check out this article.
Bryce -- what is the source of your quotation?