I don’t understand why the Shan (spelled in Burmese as Syam from the name Siam, but Burmese doesn’t have the y sound to pronounce it as written) were assigned as Chinese, while Ayutthaya (Siam) were assigned Khmer when from the Burmese perspective, they are the same people? It would be understandable if this happens in separate campaigns, but why is there such a need here?
If we go by culture, shouldn’t the Shans be closer to Burmese than Chinese? I agree that ayutthaya being Khmer is the most accurate choice though, considering that the Tai/Siamese civ was rolled back from RoR.