Of what culture region are Belgium France Luxembourg Netherlands considered part?

Belgium, France, Luxembourg, and the Netherlands are part of the northern Eurpean culture region. Specifically, the four countries make up the Frankish, or French-speaking, parts of that region. Indeed, each one of the four has French-speaking populations. The populations may be in the minority, such as in the Netherlands. But then most people in the Netherlands speak four languages: Dutch, English, French, and German.