Have you tried Southeast Asia? I’m not sure about the difference between mapping and searching, but I can get a list of plant species for the region when I search that as a place.
Yes, it’s just a dot - should probably just be removed, which I’ll do in a bit. It was created in 2012 by an unknown user (who perhaps since deleted their account). It contains no observations.
You can always string together standard places like countries and provinces to make a Southeast Asia search area, although that won’t include observations made far off of coasts.