Hi Kubur,
The brass primer flask example you show above from the Forum, ref here,
http://www.vikingsword.com/vb/showthread.php?t=21102 is described as Tuareg/Northern Sahara by the REPUTABLE Dealer I bought it from, and I have no reason to doubt him. Replies to the original thread also bear up that ID.
The flask you have has VERY similar traits to that, and I would suggest that it also is likely from the same region. I do not believe that it is Omani/Arabian. I shows no "Omani/Yemeni/Arabian type" decoration.
Stu