I am geting a feeling SE asia will be skipped again...
no..............nevar..............
anyways, if it is not Thai, then that leaves us with the Khmer and the Viets, the only two likely possibilities for Southeast Asia.
i suppose now on closer inspection, the clothes of the guys on the elephant do look... Vietnamese-ish... but not necessarily 100% Vietnamese... especially the hats... ack, that sucks, i'm a Viet, i'm supposed to know...

... the elphants, i think you couold pass them off as Vietnamese. though it could be too plain.
anyways, heres a pic of a Vietnamese elephant. compare and contrast.
if you look really close, however, maybe it could actually be Viet! but only maybe.
anyways, given that Civ has had a *few* historial discrepancies, overexaggerations, etc., etc., like having Praetorians instead of Legionaries, etc., etc., i think... well, i think that the possibility of a southeast asian civ is still quite very possible.