Soldier,
As far as I know, Muay Thai, formerly known as Mai See Sawk, Mauy Pahuyuth, Chaiya Boxing, and finally Siamese Boxing, all originated from the Thai weapons/h2h combat Martial Art of Krabi Krabong in 1350. It had no direct link to Cambodia, and neither did Muay Boran which simply means in Thai "Old or antique boxing," which was the name for the older forms of Muay Thai....as far as I know.
-But I could be wrong.