Similar to how the various regions in india have different customs and languages, the way in which head are wobbled also varies. You'll find that the further south you go in india, that more prevalent the head wobble becomes. People from states such as kerala are very enthusiastic head wobble, whereas in the mountains of northern india, the gesture is less common. Without a doubt however, the head wobble is the one universal gesture that unites all Indias. Cultural and language barriers miraculously dissolve with a wobble. It's definitely a case of "actions speak louder than words".