So why stop those things?
First you say:
"One of the best ways to stop the encroachment of the Sahara on surrounding areas would be to remove the human population of the scrubland around the desert such as the Sahel."
Then you go on to say:
"Perhaps if we could stop the corruption, tribalism, and blood feuds, plus the imprint of AIDS and drugs, then things would improve?"
It seems like the items mentioned in the second phrase will cause the first phrase to come about. Bringing these problems under control will only increase the population, which will make the desert grow larger.