Technically, East Timor isn't Asia.
Depends on how you define Asian, now, doesn't it?
No one would ever claim Ceylon, Hong Kong, Singapore, Taiwan and Japan weren't Asian, so clearly you don't have to be on the continent to be 'Asian'. I've never heard anyone claim the Philippines weren't, either. I suspect if you told Indonesia they weren't Asian, you be scorned and laughed at.
So. Half the island is Asian and the other half something else???
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Edit: To be fair, as much as I don't want to

, Timor IS on the Australian tectonic plate, and on the Australasian side of Wallace's Line. But OT3H it seems(?) not to be part of the Australian continental mass (Sahul, as some call it).