When Indians and Pakistanis say "mutton", they are talking about goat meat, which I am told by a Pakistani work colleague is a less red meat which his family and friends prefer. I learned this through a discussion about lamb at work, in which two Asian colleagues mentioned that they prefer mutton.
"In many eastern countries including the Indian sub-continent, Malaysia and Singapore the term mutton refers to goat's meat (which is also called chevon) and usually not to sheep's meat." - wikipedia mutton