I saw a a neat video recently that mapped the spread of language through Germany as a gradient, with each successive wave being understood by their neighbours b

I saw a a neat video recently that mapped the spread of language through Germany as a gradient, with each successive wave being understood by their neighbours but people at opposite ends of the spectrum having difficulty. Then national boundaries cut right through that. https://youtu.be/ilWSllUAM7U?si=t7IFX2QxdIq_jL5d https://youtu.be/ilWSllUAM7U?si=t7IFX2QxdIq_jL5d