For instance, later in the article, it mentions how it was originally thought that Burma didn't have a Bronze Age, but went from Stone Age to Iron Age without that intermediate epoch.
I read that too, but I found much more interesting that they would choose bronze for weapons rather than iron. I will assume that iron would have been far more rare than bronze, but that is just a guess on my part.
It was an interesting article, but I would like to see pictures of the weapons they found.