What were the main ingredients of the Thai cuisine before global trade? The traditional Thai cuisine was very different than the current one in a holistic perspective.

At some point in history the Thai nation started trading globally, directly or indirectly with Indians, Iranians, Arabs and also Portuguese who brought several plant species to Thailand which today some of their plant parts use as fundamental ingredients in Modern Thai Cuisine; for example, from the Americas:


Chilles
Pappaya
Corn
Tomato
Green eggplants
Tapioca
Taro
Potato


And from other places:


Japanese teas
Roses (Gulab in Thai, as in Indian and Persian)
Indian spices and legumes (as well as legume flours)
Wheat flour (probably from China or Arabia) uses to make Thai breads
Date palms used in cookies (probably from west China or Muslim states)


My problem

I didn't find a lot of clear information about the main ingredients of non globally influenced cuisine (before the Thais entered global trade).

I assume that this cuisine was overall cuisine was more similar to modern Cambodian and Vietnamese cuisine but it might be hard to prove it.

My question

What were the main ingredients of the Thai cuisine before global trade (before Thailand traded with any country outside south east Asia)?
I thought Pad Thai was one but it feels to me controversial.
Thailand, if you define it as the country where Thai is the dominant language, is a relatively new nation. Sukhothai was established in 1238 and from the beginning there was international trade. As soon as ingredients from the new world started to spread to the old world they would have arrived in "Siam/Thailand" and all other parts of Southeast Asia. It doesn't take much to spread new plant ingredients, just a few seeds and it would be quickly cultivated in mass and dispersed everywhere. It doesn't even require ongoing trade.

Of course the land was always there before the Thai arrived so if by "Thai nation" you are also talking about the Khmer, Mon, Malays and other groups that lived in and controlled the territory of modern-day Thailand, then your question does not pertain stricly to Thailand or "Thai cuisine."

Even if you look only at the Thai-speaking peoples, what do you consider "traditional Thai cuisine?" Have you considered that there is not one Thai group but multiple? Chiang Mai and northern Thailand was its own kingdom and has its own cuisine. Northeast Thailand was part of the Lao kingdoms. There are also some Shan and other tribal upland Thai groups. All are "Thai" and all have their own cusine.