In my experience
"sub-Saharan Africa" has always been used to refer to all of Africa
south of the Sahara
, not just the countries immediately bordering it. In this case Sub-Saharan Africa includes at least the following countries:
The Democratic Republic of Congo
Central African Republic
I'm not sure about places like Somalia, Ethiopia, Eritrea and Burkina Faso because, although this is shameful to admit, I'm not entirely sure where the boundary is between the Sahara and not-Sahara.
In other words, sub-Saharan Africa is all of Africa except North Africa. This might be the same in many people's minds as Arab Africa vs. black Africa (this is pure speculation on my part). I've noticed that when Afro-pessimism rears its head, it's almost always sub-Saharan Africa people are being pessimistic about. This entire, rather large region of the world is frequently stereotyped as a political and economic basket case with some nice wildlife. Do a search on just about any of the countries named above and the results will be an even mix of bad news, information to do with aid projects and tourist information. There is genuinely a lot more to it than that, but it tends not to make good copy. Roll on the African Renaissance.