As someone who's studying Ayutthaya, one common theme seems to be that a majority of surviving contemporary sources written about the Ayutthaya Kingdom come from non-native sources (i.e. European travelers, Chinese imperial court records). As someone who looks at the long historical records of civilizations like the Egyptians or the Mesopotamians, I was wondering why did states in the Middle East/West seem to develop writing much earlier than in Indian, SE Asian, or general Asian civilizations and how do they compare with the Middle East/European civilizations in this regard? Am I looking at this issue primary from a standpoint of not knowing the languages of these countries and how under-researched the histories of some of these Asian civilizations are (at least in the Western world)?
This is an interesting question! I do not myself know enough about the historiography of Asian civilisations to answer this, but I can link to some earlier threads written by users who do!
In this discussion, u/amp1212 writes about the lack of early Persian histories in comparison to Greek and Chinese ones, with important contributions from other users like u/lcnielsen. There is also this thread answered by u/Trevor_Culley about Indian sources and the possible reasons for the lack of them, specifially concerning Alexander but applicable in general to that period.
As you seem to be aware there are quite early sources from China (which I thought you would include among general Asian civilisations?), for instance Sima Qian whom u/lukeweiss wrote about in this thread some years ago. If we go yet further East there is Japan, whose earliest sources are written about by u/Legitimate_Twist linked here and u/PiousHeathen over here. For a somewhat later period u/Kelpie-Cat has made some great recommendations of court sources from the Heain period in this response.
I hope you found this helpful!