Before the invention of radio this was a property of language as well. Famously you could walk from Paris to Rome and every village could speak comfortably and naturally with its neighbors, yet by the time you got to Rome they spoke a language essentially incomprehensible to Parisians.
30 yrs ago, I rode my bike from East Berlin to Amsterdam, hopping from tiny village to tiny village. I kept out of cities so I could sleep in the forest at night and it seemed as if the the local dialect drifted town by town from deutsch to dutch
That’s a good example! I remember being on a train where a woman was reading a book in Dutch to her kids and my then 5 year old son (a German speaker) walked over to sit behind her and listen.
