My first instinct is - what mode should this be in?
If a tango, then I might assume it's actually in four sharps. Try your left-hand motif such that the notes are F# C# A C# and you'll hopefully hear what I mean. Otherwise, what you're creating is simply a rhymic drone of sorts*, using I and V. Therefore, I think you might need to establish what mode you're in and correct my assumption. The title of your piece says Arabian, so I suspect you want to allude to the locrian mode. How might you esablish that? (Or, if not the locrian mode, then how might you establish what you do intend? There are, of course, more options than simply the locrian mode.)
*I very much like rhythmic drones - too many composers go off on so many tangents far too often for my liking!