Salalah and Dhofar are historically famous for the frankincense trade. The region has tended to be rather independent over history, although this has changed since Qaboos' ascention to the throne. The Jibbali (Arabic: those of the mountains) tribes maintain a slightly distrustful stance to the government in Muscat, although this is more a stance of custom than anything else. Interestingly, the tribes speak a different language to the Arabic spoken throughout the Peninsula, although visitors are unlikely to encounter it. http://wikitravel.org/en/Salalah