Like you said, it depends on the industry, job, and region. Salaries will vary wildly as those three variables change.
I actually have a similar background:
ESL in Kazakhstan for 2 years
In Washington, D.C I was making about 22k a year working at a private ESL school, although that was technically part-time. It's hard to find a full-time ESL job outside of public schools. If you get state certified to teach in public schools, in Maryland you could get a starting salary of around 40k to 50k.
I don't have much experience with international affairs jobs, but I'm pretty sure your chances of landing anything over 35k are slim with no experience and only a bachelor's degree. Of course, if your Mandarin is truly fluent (i.e nearly native) you might be able to leverage that into considerably more. Again, that will heavily depend on your location.
I'm currently working for a government contractor doing proposal development for 35k a year (which is just barely above livable in the D.C area), which is completely unrelated to my background. The only reason I got this job was through a friend. I'm doing my masters in Applied Linguistics now because I'd like to go back to ESL teaching, but without at least a masters the jobs and salary just aren't there.