Frisian is also a popular form of language within Germany. The earliest records show Frisian was spoke as early as 1300. New Swedish and Old Danish are also found in the Northeastern Germany. Even our very own language of English derived from Germany. The English language also has ties with the language of Frisian.
Spelling becomes important when looking at the language of Germany.
I can not explain why. That is yet another unsolved mystery of the Germanic language. My guess it has to do with the dialect and change in lifestyle from one side of the country to the other. I have only selected a few of the many languages derived from the language of Germany. Language is a powerful element when understanding a culture.