Yes and No might seem to be the simplest, most primal elements in a language, a universal and straightforward system of assent. But being among the oldest elements they are also the most subject to corruption and dialectical separation.
Thus in England, to restrict our field of consideration, we have not only yes and no but also yup, yep, ya, nope, nah, aye, yay, nay, not to mention yarp and narp,uh-huh, uh-uh, and various other grunts of assent or dissent along a vanishing spectrum of intelligibility.
And now, from the east of England (apparently) we have jearse and dow. Stephen Howe, a historical linguist based at the University of Fukuoka in Japan has flown back to East Anglia to see if we really do still use the dialect forms jearse and dow for yes and no (answer: not to my knowledge, but perhaps when we have a heavy cold). He claims his father and grandfather used them, and that they might still be current in pockets of ancient population out on the fens. Anything is possible out on the Fens, of course, but I have not heard them.
Anyway, on the subject of dow more than jearse, here is a traditional English song that is close to my heart, sung, improbably enough, by the Red Army Choir.