I do not think it is from the Middle East; the general style of that gun suggests North Africa. It might have been acquired during a trip to that region or obtained in Europe (Italy or Spain would be most likely) where such guns were/are often sold in antique shops.
Also the lock is of a type and style often seen in southern Europe; as others have said, those locks were sold in North Africa and the Middle East, where they were installed on "rifles" made to suit local tastes. The makers, while they turned out functioning firearms, were usually more concerned with elaborate decoration than with reliability or accuracy, simply because in those societies, the picture of prestige and power was conveyed more by the appearance of a weapon than by its actual use. (Don't laugh too loud; we see the same thing in "barbecue" guns today!)