Correct me if I'm wrong, but isn't Yemen one of the poorest and most underdeveloped Middle Eastern countries? Perhaps that is part of why it is overlooked.
Yes. Extremely poor, notable for exasperating its already dire water situation by growing Qhat (spelling), a popular narcotic which is extremely water intensive to grow. Also notable for being the base for Islamic terrorist operations in the region for quite a while.
I've heard that AQAP has publicly stated they have some sort of alliance with Baghdadi's Islamic State. "Core Al-Qaeda," huddling in their caves in Pakistan, seem to have lost their relevance. Two of the "Boko Haram" groups, have also declared alliances with the Islamic State, one going so far as to swear allegiance to the caliphate.
