@discographer-- I think they would grow in warm areas like Florida, Texas and California.
I'm in the Midwest and I've never seen them here. I had seen them in India. I think this fruit is also common in Southeast Asia. The climate there is also very suitable for natal plum.
What I find most interesting about this fruit is that despite being called a plum, it's actually not a plum at all. The fruit just resembles plums.