Some place names fuse two words into a mazjī compound, such as حَضْرَمَوْتُ. This form of compounding can coexist with proper-name status as a cause.
سَافَرْتُ إِلَى حَضْرَمَوْتَ — I travelled to Ḥaḍramawt.
حَضْرَمَوْتَ: genitive after ilā, marked by fatḥa in its diptote treatment.
Not all compound types share this ruling; the point here is the relevant compound form.