A good question!Dutch is actually a language group. They include: Dutch, Frisian, West-Flemish and Limburgish. These are strongly related but separate languages. Call them SubLanguages. A Amsterdammer cannot understand the pure Frisian, neither the West-Flemish nor the Limburgish. For Europe and UNESCO, the four Dutch languages are separate languages, so no dialects of each other. For this, they employ a number of linguistic criteria. As far as real dialects are concerned it becomes more difficult. My former Dutch teacher claimed that originally Dutch was general in the Low Countries, without dialects, and that afterwards Dutch was “Disintegrat” in dialects. There is nothing to it. Dialects are caused by endogenous evolution but also by exogenous factors. For instance, the Gents is a real dialect that originated from the intermediate language formed by Brabants and West-Flemish. There are still between languages. In the Brussels-Leuven-Antwerpen-Gent, the economic heart of Flanders, there is now a new intermediate language based on the Brabants with strong West-Flemish and Limburg influences: the Verkavelingsvlaams. This Flemish will have more and more influence in the future, also in the Netherlands.
As far as the below languages are concerned, there is no consensus.The only reason I see is the local creolization of the Proto-Germanic, introduced into our regions by the first farmers seven thousand years ago. Those peasants came from the east. It even depends on where exactly from the east. For instance, there is “dialect” south of the Black Forest that is very similar to the West-Flemish. Is there a historic band here?
Here, in the Low Countries, communities of hunters-gatherers who spoke different non-PIE (Proto-Indo-European) languages lived.For the advent of agriculture, Europe must have spoken a mosaic of languages, dividing it into dozens of language families. A similar language situation was found by the White Europeans in North America, and it can be assumed that the language situation in Europe was once the same. Now Europe speaks for 90% PIE. The Germanic farmers who brought them into the existing hunters ‘ collectors ‘ languages were not only the Dutch sublanguages but also the Dutch language group itself. This is called creolisation of languages. Compare it to the language of Haiti: The basis was French that was creolised by the local people, the former African slaves. That language is now unintelligible for a Frenchman.
It is thought that the West-Flemish was originally spoken over the entire Dutch-Flemish coast, from South Calais to Friesland, where it passed in the Frisian.The standard Dutch originated when hundreds of thousands of Flemings, in majority Brabanders, during the Spanish Fury, the Eighty Years War, pulled to Holland and mixed their language with the local variant of the West-Flemish. The latter was recently or may still be spoken in Volendam. The resulting mixing language soon became the language of power and wealth during the golden Age. This gave this language a great influence over the Netherlands and Flanders.
For those who do not know: There is also a great variety of dialects and SubLanguages in Germany.The same applies to Spain and Great Britain. Only France has few dialects and in fact no sublanguages. Occitan is a completely different language and hardly related. The reason is that the French language is so young: barely 1000 years. Did you know that spoken French is in fact a dialect? It officially mentions the Orl茅annais and was originally only spoken in Paris and Orl茅ans. Hence the spoken French differs from the written version.