I consider Wikipedia a good source for conversational information, and to that effect: http://commons.wikimedia.org/wiki/File:World_map_of_lactose_...
Actually, a little more looking, I think I also found the Yale study it's from. Here's the power point: http://cst.yale.edu/sites/default/files/worldwide distribution of lactose intolerance, madison 2010.pptx
Anecdotally, this seems untrue. I was back in China for 2 months earlier this year and milk (fresh, no less, with expiration days of literally 3 days or less) are sold everywhere. Clearly there is a high demand for milk in mainland China (so much so that there are even brands of imported milk from Germany). This was in the capital of Beijing.