Bah, forgot to mention, another reason that Mat isn't a specific peoples reborn is that he has memories that overlap. His memories span about a thousand years, from the Trolloc wars to the War of a hundred years, and i believe it is mentioned somewhere that he has thousands of men's memories floating around in him, barring that, hundreds at least. Also, he specifically says at one point that he didn't like Artur Hawkwing in some of his memories, at a bare mimimum that would have to be 2 people that disliked him and one that liked him, three generals knowing one man would have to be three very young generals... and I think it's a lot more than three.