I've never been to Asia but Cambodia, China and Thailand. Culturally all quite appealing. India too, but there's so much I couldn't cope with.
Omg I've lived in the first two, I think the third is my 'most visited' country, and I spent two months traipsing around the fourth! I have also almost died in 3/4.

I would very much like to rubber stamp these choices - hit me up if you ever make it EAST!
Anyway, to the matter at hand, having lived on this continent for most of my adult life now, I'm kinda RUNNING OUT. I guess:
Tajikistan - confident this will happen in the next 12 months
Bhutan - if it weren't for exorbitant costs and the stymieing of adventure
Iran - if it weren't for [insert endless list of grievances]
Jordan is another that's up there and tbh far more likely than the latter two. I mean, the historian in me would happily backpack across the entire Middle East if things were different...
alas. I shoulda been born a century earlier so I coulda been a more outré T.E. Lawrence or sth.