the threat in the south

[hachem]

according to a tip in wohead, which i cannot confirm, you have to be already 89 or 90 to get this quest when finishing the sha of hatred. otherwise you will not get it, which i can confirm. getting to 89 did not make the quest available. so it would seem that it has to be done before the sha of hatred. i can't remember if it is necessary for the achievement.
edit: it is not necessary for the townlong achievement.

[cabby]

This particular quest has been a pain to figure out. There has been nothing confirmed by anyone for what makes it available. There have been some people like you who just can't get the quest even if level requirements (as posted on WoWHead) are met, and there's some like me who didn't have any problems with getting it. I personally think it has something to do with which quest lines were completed in previous zones because a lot of the people who have problems getting this one have moved to the next zone when the guide suggested to do so. When I've gone thru the MoP zones I have ignored that suggestion and just did everything in the zone guide before moving to the next zone and when I do that I have no problems with getting the quest.

Either way, this one is just a breadcrumb quest so it really isn't needed for anything.